1 

STATISTICS IN BRIEF May 2006 

The Early Reading and Mathematics Achievement of 

Children Who Repeated Kindergarten or Who Began 

School a Year Late 

U.S. Department of Education 

Institute of Education Sciences 

NCES 2006–064 

Authors: 

Lizabeth M. Malone 

ESSI* 

Jerry West 

NCES* 

Kristin Denton Flanagan 

ESSI 

Jen Park 

NCES 

Contact: 

Elvira Germino Hausken 

NCES 

elvira.hausken@ed.gov 

* At the time the work was conducted, 

Lizabeth Malone was with ESSI. She is 

currently with Teachers College, 

Columbia University. At the time the 

work was conducted, Jerry West was 

with NCES. He is currently with 

Mathematica Policy Research, Inc. 

Introduction 

 

Most children enter kindergarten when they are 5 years of age and move into first 

grade when they are 6. This time period is marked by great developmental change 

(Sameroff and Haith 1996), and children differ in what they can and cannot do 

socially, physically, and cognitively. Therefore, parents and educators are concerned 

whether certain children will have the knowledge and skills at age 5 to succeed in 

kindergarten. Over the years, policies and practices have emerged that are intended 

to improve children’s early school experiences by giving them more time to develop 

and mature (e.g., changing age of entry requirements, transitional grades, readiness 

testing). Two such kindergarten enrollment strategies are retaining children for a 

second year of kindergarten and delaying the start of their first year of kindergarten. 

This report uses data from the Early Childhood Longitudinal Study, Kindergarten 

Class of 1998–99 (ECLS-K) to examine the relationship between kindergarten 

enrollment status (e.g., repeating kindergarten or delaying entry into kindergarten) 

and children’s spring first grade reading and mathematics achievement. 

 

Background 

 

For the most part, children must be 5 years old to enroll in kindergarten (Education 

Commission of the States 1999). Based on school regulation and the child’s 

development, parents and schools make decisions about when children should begin 

kindergarten; a child may start kindergarten when age-eligible, wait a year, or start 

early relative to the age requirements. In addition to timing children’s first entry into 

school, parents and educators make promotion decisions about children at the end of 

the school year; some children go on to the next grade while others repeat 

kindergarten. Given these factors, the U.S. kindergarten population can be grouped 

according to their enrollment status. 

• Every school year there are children who repeat kindergarten. Some children 

repeat due to academic and/or social concerns while others are in their second 

year of a 2-year kindergarten program (e.g., junior kindergarten, developmental 

kindergarten, kindergarten plus).1

 Children who repeat kindergarten are often 

older than most of their new classmates who are beginning kindergarten for the 

first time. 

• Some non-repeating children begin their first year of kindergarten a year later 

than is typical. These children were age-eligible for kindergarten the previous 

year and were likely held out by their parents to allow an extra year to mature or 

perhaps because of developmental difficulties. Delayed entry kindergartners are 

beginning their first year in formal schooling; however, since their entry was 

delayed, they tend to be older than their peers beginning kindergarten on time. 

_____________________________________________________________________ 

1

At times, schools will refer to a second year of kindergarten with a school-specific term, such as “transition K.” If 

the parent reports this as repeating kindergarten (e.g., a second year of kindergarten) then the children are counted as 

repeaters in this report. 
2 

• The majority of kindergartners (88 percent) 

begin formal schooling when they are old 

enough according to age requirements for 

their school or school district. These firsttime, on-time kindergartners tend to be born 

in the months that usually define age 

eligibility (e.g., the children are five years of 

age by September, October, November, or 

December, depending on the cut-off of the 

state) but could also include children who just 

missed most schools’ or districts’ age cut-off 

for the previous year (meaning, these children 

may be slightly older than their classmates, 

but are still considered first-time, on-time 

kindergartners). 

Both repeat (retention) and delayed entry 

practices are largely grounded in the belief that 

more time will allow children to arrive better 

prepared for school academically and socially 

(Ilg and Ames 1965; Kundert, May, and Brent 

1995). For example, if kindergarten children do 

not achieve the knowledge, skills, and social 

maturity deemed necessary for first grade, 

attending a second year of kindergarten will 

allow them time to gain these skills. This is done 

in hopes that retaining them in kindergarten will 

prevent later school failure without negative 

social consequences (Dennebaum and Kulberg 

1994; Shepard 1989). Some parents choose to 

delay their child’s entry to kindergarten so that 

they will perhaps have an advantage over their 

on-time, younger classmates (Meisels 1992; 

Shepard and Smith 1988). 

The effectiveness of these practices, retention in 

particular, however, has been called into 

question (Dennebaum and Kulberg 1994; 

Kundert, May, and Brent 1995; Reynolds 1992). 

Some research has shown kindergarten repeaters 

perform worse in their second year of 

kindergarten than promoted peers who were 

recommended for retention in kindergarten 

(Dennebaum and Kulberg 1994), perform no 

differently than delayed-entry children later in 

school (e.g., second and fifth grade) (Kundert, 

May, and Brent 1995), and perform worse in 

reading and mathematics in fourth grade 

(Reynolds 1992). Other researchers suggest 

retention may have short-term benefits. Children 

appear to make larger cognitive gains in the year 

they repeat as compared to their first year 

through a grade (e.g., first-grade retention as 

studied by Alexander, Entwisle, and Dauber 

1994). Recently, a review of the existing 

research note the need for future research that 

considers child and program characteristics 

when evaluating outcomes of retention and 

delayed entry practices (Jimerson 2001). These 

research findings have led many investigators to 

draw competing and even conflicting 

conclusions regarding grade retention and 

delayed entry. 

Types of Comparisons 

Conclusions depend on one’s perspective on the 

practice’s intended purpose (e.g., delaying for 

advantage versus retaining to allow the child to 

reach grade level achievement). The research on 

kindergarten retention and delayed entry usually 

takes one of two approaches—same age versus 

same grade comparisons. Same age comparisons 

examine the performance of retained or delayedentry children relative to “promoted” peers of 

the same age (i.e., in a different grade). Same 

grade comparisons investigate how retained or 

delayed-entry children are performing relative to 

their peers in the same grade. For example, one 

study, using both the same age and same grade

approach, found that retaining children or 

holding them out a year does not produce lasting 

academic advantages, and retaining children 

may have potentially negative social 

consequences (Dennebaum and Kulberg 1994). 

Since these children perform no differently than 

children who are promoted or their current 

classmates, the study’s authors concluded that 

retention and delayed entry practices should be 

discontinued. In another example, using the 

same age approach, researchers found that 

children who repeat a grade or whose entry is 

delayed perform similar to their on-time 

classmates and promoted peers, albeit 1 year 

later. In this case, researchers interpreted their 

findings as support for the effectiveness of these 

practices (Alexander, Entwisle, and Dauber 

1994). 

This report uses the same grade approach. The 

same grade approach allows comparisons to 

children’s current classmates with whom they 
3 

will most likely spend future school years. This 

permits conclusions concerning the retained or 

delayed entry child’s mastery of material for a 

given grade level as compared to the majority. 

The same grade approach can also be used to 

compare children to how their promoted peers 

did the year previously. If children who repeat 

kindergarten or whose entry is delayed perform 

similarly to promoted peers, this provides 

information on their achievement relative to a 

grade before moving on. Comparing children to 

promoted peers in another grade (i.e., same age

approach) does not provide information on how 

well children mastered current grade skills. 

Same grade comparisons may be more 

appropriate than same age comparisons because 

they focus on achievement for the same type of 

material, but these comparisons still have 

limitations. In this approach, the children being 

compared are no longer the same age. The child 

repeating kindergarten or whose entry is delayed 

is generally 1 year older than his/her current 

classmates and generally 1 year older than their 

promoted peers were in the previous year when 

in that grade. The retained child has also had 2 

years of exposure to the kindergarten setting and 

educational materials. Findings using this 

approach tend to find short- term benefits for 

retention (e.g., higher performance), with 

benefits diminishing over time (Peterson, 

DeGracie, and Ayabe 1987). 

This report takes a same grade approach by 

comparing children who repeat kindergarten and 

children whose entry is delayed to their 

classmates who are entering kindergarten for the 

first time, on time (i.e., when age-eligible). 

Research Questions 

 

This report is framed around the following 

research questions: 

• How prevalent is kindergarten retention? 

How prevalent is the practice of delayed 

kindergarten entry? 

• Do children in these different enrollment 

groups vary in terms of child and family 

characteristics (i.e., sex, age at time of 

assessment, children’s race/ethnicity, 

presence of a diagnosed developmental 

difficulty, family poverty status, parental 

education, preschool experience, and 

kindergarten program type (i.e., half-day or 

full-day))? 

• What is the relationship between children’s 

kindergarten enrollment status and children’s 

first grade reading and mathematics 

achievement? 

Data Source 

The ECLS-K is a nationally representative 

sample of approximately 21,000 children who 

entered kindergarten in the fall of 1998. The 

sample reflects all children in kindergarten in the 

fall of 1998, including children from various 

racial/ethnic and language backgrounds, children 

entering kindergarten for the first time, and 

those repeating kindergarten. Sampling for the 

ECLS-K was based on a dual frame, multi-stage 

sampling design. The first stage of sampling 

involved the selection of 100 primary sampling 

units (PSU, counties or groups of counties) from 

a national sample of PSUs. Schools with 

kindergarten programs were then selected within 

the PSUs, and children were sampled from the 

selected schools. 

Estimates in this report refer to children who 

were in kindergarten in the fall of 1998, who 

were promoted to first grade in the fall of 1999,1

and since the main dependent variables of 

interest are reading and mathematics 

achievement, all children who received the 

English direct reading and mathematics

 

1

As initially planned, the ECLS–K followed children in from the 

1998-99 school year through the 2003-04 school year, no matter 

the grade they were in. Most children stayed on grade level (e.g., 

kindergarten in 1998-99; first grade in 1999-2000); however some 

children were retained and some skipped a grade. To keep the 

sample consistent across all analyses presented in this report, this 

report uses the sample of children in kindergarten in 1998-99 and 

who were promoted to first grade in 1999-00 (approximately 95 

percent of the sample of kindergartners went on to first grade in 

1999-00). It should also be noted that children who entered 

kindergarten early for their age in the fall of 1998 are not included 

in this report (given their small number (2 percent) and this 

report’s focus of comparing children who entered on time, were 

retained, and those who were delayed). 
4 

assessment in the fall of kindergarten, spring of 

kindergarten, and spring of first grade.2

 

Findings 

Findings are presented according to the research 

questions. For more information on the statistical 

approaches utilized in this report, please see the 

Methodology and Technical Notes section. 

Prevalence 

In the fall of 1998, 5 percent of all children in 

kindergarten were repeating kindergarten, and 6 

percent were attending kindergarten for the first 

time even though they were age-eligible to do so 

a year earlier (i.e., delayed entry) (data not 

shown in tables) (figure 1).3

 

Figure 1. Percent of children, by kindergarten enrollment status: Fall 1998 

NOTE: Detail may not sum to totals because of rounding. 

SOURCE: U.S. Department of Education, National Center for Education Statistics, Early Childhood Longitudinal Study, Kindergarten Class of 

1998-99, (ECLS-K), Longitudinal Kindergarten-First Grade Public-Use Data File. 

 

2

As mentioned, the ECLS–K sample reflects all children in kindergarten in the fall of 1998; this includes children from all backgrounds and all 

languages in the United States. Information was collected from children, their parents, teachers, and schools no matter their language background. 

However, this report uses information from the direct child assessment. The ECLS–K direct child reading assessment was administered in 

English. To be sensitive to the needs and capabilities of all children in the sample, an English language proficiency screener was administered if 

the school records indicated that the child’s primary language was not English. If it was determined that a child was not English language 

proficient, the child was not administered the direct reading and mathematics assessment. Therefore, children who were not English proficient at 

kindergarten entry are not included in this analysis. 

3

Prevalence estimates are based on the weighted statistics from the analytic sample created for this report. 

First time, 

on-time 

88%

Repeating 

kindergarten 

5%

First time, 

delayed 

6% 

First time, 

early 

2%
5 

Difference in Enrollment Status by Child 

and Family Characteristics 

Children who repeated kindergarten are less 

likely to have attended preschool the year prior 

to kindergarten (63 versus 71 percent) than 

children who entered kindergarten on time (table 

1). Children who repeated kindergarten 

compared to children who began on time are 

more likely to be male (66 versus 49 percent); 

more likely to have diagnosed developmental 

difficulties by the end of first grade (22 versus 9 

percent); more likely to live in a family 

considered to be in poverty (19 versus 11 

percent); and more likely to have parents with 

less than a high school education (17 versus 7 

percent). They are also more likely than children 

who entered on time to be in full-day 

kindergarten programs during their retention 

year (i.e., second year of kindergarten) (73 

versus 56 percent). These findings are consistent 

with previous research (Zill, Loomis, and West 

1997). While earlier research suggests that 

children who repeat kindergarten may be more 

likely to be racial/ethnic minorities, the current 

analyses found detected no differences in the 

extent to which Black children were represented 

among repeaters compared with the on-time 

group (table 1). 4,5

Children whose kindergarten entry was delayed 

are more likely than children who started on 

time to be male (60 versus 49 percent); more 

likely to be White (72 versus 64 percent) 

(consistent with earlier findings in Zill, Loomis, 

and West 1997); and are less likely to have 

attended preschool the year prior to kindergarten 

(65 versus 71 percent) (table 1). They are more 

likely than children who began kindergarten on 

time to have parents with a bachelor’s degree or 

higher (38 versus 31 percent) (table 1). Previous 

literature has suggested income differences 

(Meisels 1992), but the current analyses suggests 

no difference by poverty status between children 

whose kindergarten entry was delayed and their 

 

4

In bivariate analysis of ECLS-K data a substantive difference 

means a difference of 5 percentage points or more between 

compared groups. 

5

When interpreting potential racial/ethnic differences, it should be 

kept in mind that the analytic sample was constrained to children 

assessed in English, reducing the number of Hispanic and Asian 

Pacific Islander children included in the analysis. 

classmates who entered kindergarten on time. 

There was no difference detected for delayedentry children when compared to on-time 

children by whether a child had a developmental 

difficulty. 

Association of Enrollment Status to 

Children’s Spring First Grade Reading 

and Mathematics Achievement 

To investigate the relationship between 

enrollment status and achievement beyond what 

may be explained by certain child and family 

characteristics, the analysis included a series of 

linear regressions using the characteristics found 

in table 1 and children’s fall kindergarten 

achievement as control variables,6

 with 

enrollment status as the explanatory variable and 

reading and mathematics achievement as the 

outcome variables.7

Much of the literature and discussion 

surrounding retention and delayed school entry 

concerns their effects on children’s achievement 

and development beyond the first year after 

retention or delayed entry (Peterson, DeGracie, 

and Ayabe 1987; Shepard and Smith 1988). 

Therefore, this part of the analysis focuses on 

children’s spring first grade achievement by 

their kindergarten enrollment status. 

Achievement is measured by children’s overall 

scale scores and three specific skills in reading 

and mathematics at the end of first grade.8

 

In reading, children who repeated kindergarten 

 

6

Over 90 percent of children were assessed in a 2-month period at 

each data collection. Therefore, date of assessment was not 

included as a control variable in this analysis. 

7

The regression analyses are intended to show how the variables of 

interest for this study interact in a multivariate setting. Readers 

should not draw causal inferences from the regression results in 

this report, since apparent relationships can change based on the 

particular independent variables examined. Also, the current study 

does not allow the examination of how delayed-entry children 

would have performed in kindergarten one year earlier when they 

were eligible to start school. 8

The ECLS–K cognitive battery was designed as a kindergartenfirst grade assessment. As the present analyses focuses on first 

grade achievement, this report examines only those specific 

reading and mathematics skills that the majority of children tend to 

acquire across the first grade year (i.e., ending sounds, sight words, 

words in context, ordinality, addition/subtraction, and 

multiplication/division). 
6 

are behind their classmates who began 

kindergarten on time by the end of first grade. 

When such factors as children’s initial 

achievement, sex, age, family poverty status, 

and kindergarten program type (e.g., full-day) 

are controlled,9

 children who repeated 

kindergarten demonstrate lower overall reading 

knowledge and skills (table 3). Children who 

repeated kindergarten also appear less likely to 

possess specific reading skills that are typical of 

first grade (i.e., understanding the letter-sound 

connection at the end of word, sight-word 

recognition, and understanding words in 

context) (table 3). Similar associations exist in 

mathematics by enrollment status (table 4). 

Children who repeated kindergarten demonstrate 

lower overall mathematics knowledge and skills 

(table 3). Children who repeated kindergarten 

also appear less likely to possess specific 

mathematics skills that are typical of first grade 

(i.e., ordinality, addition and subtraction, 

multiplication and division) (table 4). 

In reading, at the end of first grade, when such 

factors as children’s initial achievement, sex, 

age, family poverty status, and kindergarten 

program type (e.g., full-day) are controlled,10

children whose kindergarten entry was delayed

demonstrate slightly higher overall reading 

knowledge and skills (table 3). Children whose 

kindergarten entry was delayed also appear more 

likely to possess certain specific reading skills, 

typical of first-graders (i.e., understanding the 

letter-sound connection at the end of word and 

understanding words in context) and less likely 

to possess others (i.e., sight word recognition) 

(table 3). In mathematics in the spring of first 

grade, opposite associations exist than described 

in reading. In mathematics, in the spring of first 

grade, children whose kindergarten entry was 

delayed demonstrate lower overall mathematics 

 

9

Controls included children’s sex and age at school entry in fall 

1998, their race/ethnicity, the presence of a diagnosed 

developmental difficulty, highest parental education, family 

poverty level, fall kindergarten achievement, preschool experience 

(center-based or Head Start), and fall 1998 kindergarten program 

type (i.e., full day versus half day). 

10Controls included children’s sex and age at school entry in fall 

1998, their race/ethnicity, the presence of a diagnosed 

developmental difficulty, highest parental education, family 

poverty level, fall kindergarten achievement, preschool experience 

(center-based or Head Start), and fall 1998 kindergarten program 

type (i.e., full day versus half day). 

knowledge and skills (table 4). Children whose 

kindergarten entry was delayed also appear less 

likely to possess certain specific mathematics 

skills that are typical of first-graders (i.e., 

ordinality, addition and subtraction, 

multiplication and division) (table 4). 

Summary 

Previous reports from the Early Childhood 

Longitudinal Study, Kindergarten Class of 1998-

99 (ECLS-K) document the differing abilities 

and early experiences of kindergartners and first 

graders (Denton and West 2002; West, Denton, 

and Germino Hausken 2000; West, Denton, and 

Reaney 2001). The current report focuses on 

differences in child characteristics and academic 

achievement by kindergarten enrollment status. 

It once again highlights the diverse nature of 

children who constitute the kindergarten 

population. Among the findings in this report 

are: 

• The percentage of children who repeat 

kindergarten or experience delayed school 

entry appears consistent with previous 

estimates (Graue and DiPerna 2000; Zill, 

Loomis, and West 1997), with approximately 

5 percent of children repeating kindergarten 

and 6 percent starting kindergarten a year 

later when first age-eligible. 

• Children who repeat kindergarten, start 

kindergarten late, and who start on time differ 

in several important ways: 

- Children who repeat kindergarten are more 

likely to come from less advantaged 

backgrounds; more likely to have parents 

with less than a high school education; 

more likely to be living in poverty; less 

likely to have attended preschool; more 

likely to have attended full-day 

kindergarten programs during the 1998–99 

school year; and, are more likely to have a 

diagnosed developmental difficulty than 

children who entered kindergarten on time 

(table 1). 
7 

- Children who started kindergarten late (i.e., 

delayed entry) were more likely to be 

male; more likely to be White; more likely 

to have more educated parents (i.e., 

bachelor’s degree or higher); and less 

likely to have attended preschool than 

children who entered on time (table 1). 

• At the end of first grade, children who 

repeated kindergarten have lower reading and 

mathematics knowledge and skills than those 

who started on time (tables 3 and 4). 

• At the end of first grade, children whose 

kindergarten entry was delayed demonstrate 

slightly higher reading knowledge and skills 

than those who started on time (table 3). In 

mathematics at the end of first grade, children 

whose kindergarten entry was delayed 

kindergarten are behind their classmates who 

began kindergarten on time (table 4). 

Retaining children for a second year of 

kindergarten is based on the belief that the 

additional time will allow children to gain the 

cognitive and social skills necessary for first 

grade and later elementary school. However, by 

as early as the end of first grade, children who 

repeated kindergarten demonstrate reading and 

mathematics knowledge and skills below their 

non-retained kindergarten classmates. 

Similar to kindergarten retention, delaying 

children’s entry to school can be viewed as 

providing children with extra time to develop 

socially and cognitively for school. 

Future Analyses of the ECLS-K Data 

Continued investigation of these children’s 

academic achievement and educational 

experiences using the ECLS-K data can further 

clarify the association of these early practices to 

subsequent achievement in school. For example, 

consistent with findings presented in this 

Statistics in Brief, Hong and Raudenbush (2005) 

suggest that kindergarten retention may not 

improve children’s early academic outcomes. 

Using the ECLS-K data, Hong and Raudenbush 

modeled what retained kindergartners’ 

achievement would have been had they been 

promoted to first grade on time and found that 

retention in kindergarten may leave retainees 

even further behind. Hong and Raudenbush also 

suggest that advancing children to the next grade 

would have increased their chances and 

opportunities for learning more and achieving 

higher academic scores.11

Methodology and Technical Notes 

Survey Methodology 

The Early Childhood Longitudinal Study, 

Kindergarten Class of 1998–99 (ECLS-K), is 

being conducted by Westat for the U.S. 

Department of Education, National Center for 

Education Statistics (NCES). It is designed to 

provide detailed information on children’s early 

school experiences. The study began in the fall 

of the 1998-99 school year. As initially planned, 

the children participating in the ECLS-K are 

being followed longitudinally through the fifth 

grade. NCES has revised the original 

kindergarten through fifth grade design, and the 

ECLS-K will now follow children through their 

8th grade year in school. 

Sample Design 

A nationally representative sample of 21,260 

children enrolled in 1,277 kindergarten 

programs during the 1998–99 school year was 

selected to participate in the ECLS-K. The 

children attended both public and private 

kindergartens that offered full-day and half-day 

programs. The sample included children from 

different racial/ethnic and socioeconomic 

backgrounds, and included oversamples of 

Asian and Pacific Islander children, private 

kindergartens, and private kindergartners. 

 

11This Statistics in Brief looked at children who were retained 

during the 1997-98 school year and were in kindergarten for the 

second time in 1998-99 and at their actual performance in first 

grade. The Hong and Raudenbush (2005) article looked at children 

who were retained during the 1998-99 school year and at their 

actual performance in their second year of kindergarten (1999-

2000) and their modeled potential performance had they been 

promoted to first grade in 1999-2000. 
8 

Sampling for the ECLS-K involved a dualframe, multistage sampling design. The first 

stage of sampling involved the selection of 100 

primary sampling units (PSU) from a national 

sample of PSUs. The PSUs were counties and 

county groups. Public and private schools were 

then selected within the PSUs, and children were 

sampled from the selected schools. Public 

schools were selected from the Common Core of 

Data, a public school frame, and private schools 

were selected from a private school frame 

developed from the Private School 

Survey.12 Approximately 23 kindergartners were 

selected on average in each of the sampled 

schools. 

The first grade sample included children who 

had participated at least once during the base 

year. Participation was defined as having a 

completed parent interview or a direct child 

assessment. All students still enrolled in their 

base-year schools were recontacted; a 50 percent 

subsample of base-year students who had 

transferred from their kindergarten school was 

followed. For information on subsampling of 

transfer children (i.e., movers), refer to the 

ECLS-K First Grade Public-Use Data Files 

User’s Manual. 

Analytic Sample 

Estimates in this report are based on data 

collected from and about children who were in 

kindergarten during the 1998-99 school year, 

who did not enter early, who were promoted to 

first grade in the fall of 1999, and who were 

administered the direct child assessment in 

English in the fall and spring of kindergarten 

and in the spring of first grade. A total of 12,495 

children in the ECLS-K sample satisfied these 

conditions and were used in the analyses 

conducted for this report. 

Approximately 93 percent of the sample was 

promoted to first grade on time in the fall of 

1999. Approximately 69 percent of Hispanic 

children and 84 percent of Asian children were 

 

12During the spring of 1998, Westat identified new schools that 

were not found on either frame. A sample of these schools was 

included in the ECLS–K school sample. 

assessed in English in the fall and spring of 

kindergarten and the spring of first grade.

Response Rates 

A total of 944 of the 1,277 originally sampled 

schools participated during the base year of the 

study. This translates into a weighted school 

response rate of 74 percent for the base year of 

the study. The school response rate during the 

spring of the base year (74 percent) was higher 

than during the fall (69 percent), due to some of 

the schools that originally declined to participate 

deciding to participate in the spring. Nearly all 

(99 percent) of the schools that participated in 

the fall of the base year also participated in the 

spring. 

The child base-year completion rate was 92 

percent (i.e., 92 percent of the children were 

assessed at least once during kindergarten). The 

parent base-year completion rate was 89 percent 

(i.e., a parent interview was completed at least 

once during kindergarten). Thus, the overall 

base-year response rate for children was 68 

percent (74 percent x 92 percent), and the baseyear response rate for the parent interview was 

66 percent (74 percent x 89 percent). About 95 

percent of the children and 94 percent of the 

parents who participated in the fall of 

kindergarten also participated in the spring. 

About 88 percent of the children and 85 percent 

of the parents who were eligible for the spring 

first grade collection participated. 

A nonresponse bias analysis was conducted to 

determine if substantial bias is introduced due to 

school nonresponse. The results of these 

analyses are summarized in the ECLS-K Base 

Year Public-Use Data Files User’s Manual and 

the ECLS-K First Grade Public-Use Data Files 

User’s Manual.

13 Findings from these analyses 

suggest that there is not a bias due to school 

nonresponse. 

 

13For more information, also refer to Rock and Pollack (2002). 
9 

Data Reliability 

Estimates produced using data from the ECLS-K 

are subject to two types of error, sampling and 

nonsampling errors. Nonsampling errors are 

errors made in the collection and processing of 

data. Sampling errors occur because the data are 

collected from a sample rather than a census of 

the population. A detailed discussion of these 

types of errors can be found in America’s 

Kindergartners (West, Denton, and Germino 

Hausken 2000). 

Standard Errors and Weights 

In order to produce national estimates from the 

ECLS-K data collected during the kindergarten 

and first-grade years, the sample data were 

weighted. Weighting the data adjusts for unequal 

selection probabilities at the school and child 

levels and adjusts for school, child, teacher, and 

parent nonresponse. The approach used to 

develop weights for the ECLS-K is described in 

the ECLS-K Base Year Public-Use Data Files 

User’s Manual and the ECLS-K First Grade 

Public-Use Data Files User’s Manual. 

The child panel weight (C124CW0) is the 

weight used to produce all estimates found in 

this report. Only those cases with completed 

child assessments14 in both fall and spring of 

kindergarten and spring of first grade are 

included in this weight. It sums to the population 

of all children who attended kindergarten in the 

fall of 1998. However, in this report it sums to 

the population of children who attended 

kindergarten in the fall of 1998 and were 

promoted to first grade in the fall of 1999 and 

were assessed in English in all three rounds of 

data collection. 

In addition to properly weighting the responses, 

special procedures for estimating the statistical 

significance of the estimates were employed 

because the data were collected using a complex 

sample design. Complex sample designs, like 

that used in the ECLS-K, result in data that 

violate the assumptions that are normally 

 

14A completed child assessment is an assessment in which the child 

has height or weight or a scoreable reading, mathematics, or 

general knowledge assessment within the given round (i.e., fall 

kindergarten, spring kindergarten, spring first grade). 

required to assess the statistical significance of 

the results. Frequently, the standard errors of the 

estimates are larger than would be expected if 

the sample was a simple random sample and the 

observations were independent and identically 

distributed random variables. 

Replication methods of variance estimation were 

used to reflect the actual sample design used in 

the ECLS-K. A form of the jackknife replication 

method (JK2) using 90 replicates was used to 

compute approximately unbiased estimates of 

the standard errors of the estimates in the report, 

using WesVar version 4.2. The jackknife 

methods were used to estimate the precision of 

the estimates of the reported national 

percentages and means. 

Statistical Procedures 

Comparisons made in the text were tested for 

statistical significance to ensure that the 

differences are larger than might be expected 

due to sampling variation. When comparing 

estimates at one point in time (e.g., fall 

kindergarten cognitive achievement) or between 

categorical groups (e.g., sex, race/ethnicity, 

preschool experience, family poverty status), t

statistics were calculated. The formula used to 

compute the t statistic was 

t = Est1 – Est2 / SQRT[(se1)

2 + (se2)2

] 

where Est1 and Est2 are the estimates being 

compared and se1 and se2 are the corresponding 

standard errors. 

Ordinary least squares regression analysis was 

used to examine the association of enrollment 

status to achievement controlling for certain 

variables. Analyses focused on B 

(unstandardized coefficients) and statistical 

significance of the B coefficient tested by the t 

statistic. 

All differences cited in the text of this report 

were significant at the .05 level. For the 

bivariate analysis, differences reported represent 

both a statistical difference and a difference at 

least 5 percentage points. This guideline for 

bivariate differences, of reporting differences 
10

when they are both statistically significant and 5 

percentage points different, is typical of NCES 

reports and presentations using information from 

the ECLS-K. 

Constructs and Variables Used in the 

Analyses 

Family and Child Characteristics 

Parents/guardians were asked to provide key 

information about their children on subjects such 

as family demographics (e.g., age, relation to 

child, race/ethnicity), family structure 

(household members and composition), 

experiences in early care and education, and 

parental education. A computer-assisted 

interview was conducted with the sampled 

child’s primary caregiver (usually the child’s 

mother). Most of the interviews were conducted 

by telephone, though some were conducted inperson when respondents did not have a 

telephone or were reluctant to be interviewed by 

telephone. The same instrument was used 

regardless of the mode of interview. 

Children’s Cognitive Knowledge and Skills 

The ECLS-K direct child cognitive assessment 

was administered using computer-assisted 

personal interviewing (CAPI), administered oneon-one with each child. The assessment included 

two cognitive domains (reading and 

mathematics). The ECLS-K battery was a twostage assessment approach, in which the first 

stage in each domain contained a routing test 

that determined a child’s approximate skills. 

According to the child’s performance on the 

routing test, the child was administered the 

appropriate skill level assessment for that 

domain (the second stage). The reading and 

mathematics assessments had three skill levels. 

In each round, children were administered the 

routing stage and the appropriate skill level stage 

in the fall of kindergarten, the spring of 

kindergarten, and the spring of first grade. (For 

more information on the cognitive assessment 

refer to Rock and Pollack 2002). 

To be sensitive to the needs and capabilities of 

the children in the sample, an English language 

proficiency screener, called the Oral Language 

Development Scale (OLDS), was administered 

if school records indicated that the child’s home 

language was not English. The child had to 

demonstrate a certain level of English 

proficiency to be administered the cognitive 

assessment in English. The cognitive knowledge 

and skills estimates in this report are based on 

those children who were assessed in English in 

both the fall and the spring of kindergarten, and 

the spring of first grade. For the analytic sample 

utilized in this report (kindergartners in the 

1998–99 school year who did not start early and 

were promoted to first grade in the fall of 1999), 

in terms of English assessment by race/ethnicity, 

approximately 69 percent of Hispanic children 

and 84 percent of Asian children were assessed 

in English in fall and spring of kindergarten and 

spring of first grade.15 For more details, see the 

ECLS-K Base Year Public-Use Data Files 

User’s Manual and the ECLS-K First Grade 

Public-Use Data Files User’s Manual. 

Scale scores. Item Response Theory (IRT) was 

employed to calculate scores that could be 

compared regardless of which second stage form 

a child took. The items in the routing test, plus a 

core set of items shared among the different 

second stage forms, made it possible to establish 

a common scale. IRT uses the pattern of right, 

wrong, and omitted responses to the items 

actually administered in a test, and the difficulty, 

discriminating ability, and “guess-ability” of 

each item, to place each child on a continuous 

ability scale. It is then possible to estimate the 

score the child would have achieved if all of the 

items in all of the test forms had been 

administered. The reliability of the estimates of 

 

15Based on the analytic sample used in this report (i.e., children on 

the kindergarten and first grade longitudinal file with a valid full 

sample weight (C124W0) and who were promoted to first grade in 

1999-00)—approximately 48 percent of Hispanic children did not 

receive the OLDS and went directly to the English direct cognitive 

assessment (i.e., school records did not indicate the need for the 

OLDS), approximately 52 percent of Hispanic children received 

the OLDS (21 percent passed the OLDS; 31 percent did not pass 

the OLDS); and, approximately 46 percent of Asian children did 

not receive the OLDS and went directly to the English direct 

cognitive assessment, approximately 54 percent of Asian children 

received the OLDS (40 percent passed the OLDS, 14 percent did 

not pass the OLDS). 
11

reading and mathematics in all three data 

collections are as follows (IRT-based theta): 

reading = .9, mathematics = .9. 

Proficiency probability scores. Proficiency 

scores provide a means of distinguishing status 

or gain in specific skills within a content area 

from the achievement measured by the IRT scale 

scores. Clusters of four test questions having 

similar content and difficulty were included at 

several points along the score scale of the 

reading and mathematics tests. A child was 

assumed to have mastered a particular level of 

proficiency if at least three of the four items in 

the cluster were answered correctly, and to have 

failed at this level if two or more items were 

wrong. Clusters of items provide a more reliable 

test of proficiency than do single items because 

of the possibility of guessing. It is very unlikely 

that a child who has not mastered a particular 

skill would be able to guess enough answers 

correctly to pass a four-item cluster. These 

scores are computed using performance in each 

subject. The nature of the two-stage test is that 

not all children receive all items. To calculate 

proficiency estimates for all children, an IRT 

model was employed. For the purpose of IRT 

calibration, the item clusters were treated as 

single items. The hierarchical nature of the skill 

sets justified the use of the IRT model in this 

way. Gains in probability of mastery at each 

proficiency level allow researchers to study not 

only the amount of gain in total scale score 

points but also where along the scale different 

children are making their largest gains in 

achievement during a particular time interval. 

In reading, the proficiency levels are named as 

follows: (1) letter recognition, (2) beginning 

sounds, (3) ending sounds, (4) sight words, and 

(5) words in context. Letter recognition is as it 

sounds—the ability of children to recognize 

their letters. Beginning sounds and ending 

sounds refer to children’s ability to understand 

the letter-sound relationship at the beginning and 

at the ending of words. Sight words refer to 

children’s ability to recognize whole words by 

sight and read them aloud. Words in context

refer to children’s ability to read simple short 

passages of text with a missing word, and insert 

the correct missing word. 

In mathematics, the proficiency levels are named 

as follows (their names reflect the most complex 

mathematical construct contained in the 

proficiency): (1) number and shape, (2) relative 

size, (3) ordinality and sequence, (4) 

add/subtract, and (5) multiply/divide. Number 

and shape refers to children’s ability to 

recognize single-digit numbers and basic shapes. 

Relative size refers to children’s ability to count 

beyond 10, recognize the sequence in basic 

patterns, and compare the relative size of 

objects. Ordinality and sequence means that 

children can recognize two-digit numbers, 

identify the next number in a sequence, and 

identify the ordinal position of an object. 

Addition and subtraction means children can 

perform simple addition and subtraction 

problems. Multiplication and division refers to 

children’s ability to perform simple 

multiplication and division operations. The 

addition, subtraction, multiplication, and 

division items are presented in the form of word 

problems with picture support and in numerical 

statements. 

Derived Variables 

A number of variables used in this report were 

derived by combining information from one or 

more questions in the ECLS-K parent 

questionnaire or from other study sources. The 

derivation of key variables is described in this 

section. If the actual variable exists on the 

ECLS-K Public-Use Data file, the name of the 

variable is presented after the description in all 

capital letters within brackets. If the variable 

was derived specifically for this report, that is 

also noted in brackets. 

1998 kindergarten enrollment status. This 

variable was created through information 

collected in the Parent Involvement with the 

Child’s School section of the fall kindergarten 

parent interview. It is based on (a) year of 

kindergarten attendance (e.g., first, second) 

(P1FIRKDG) and (b) timing of school entry 

(e.g., waited, when old enough) (P1WHENEN; 

PIQ070). P1FIRKDG is a recoded variable from 

question PIQ080, collapsing year of 

kindergarten attendance into a dichotomous 

yes/no variable for whether the child is a first-
12

time kindergartner. If the parent reported that 

this was the child’s second or greater year of 

kindergarten (P1FIRKDG=2), the child’s 

enrollment status was defined as repeating

kindergarten. If it was the child’s first year of 

kindergarten (P1FIRKDG=1), the timing 

question (i.e., PIQ070) was examined. For these 

first-time kindergartners, if parents reported 

waiting to enroll their child in kindergarten, the 

child’s enrollment status was defined as delayed 

entry; if parents reported enrolling their child 

when old enough, the child’s enrollment status 

was defined as on time.

16 [variable derived for 

this report, not presented on data file] 

Children’s sex. This variable was constructed 

by comparing information provided by the 

parents as part of the parent interview and 

information from staff in the field (via the field 

management system) who administered the 

direct assessments. If parent interview 

information was missing, this variable was 

completed by relying on information from the 

field management system. [GENDER] 

Children’s age at entry to kindergarten (fall 

1998). This variable used two variables—month 

and year of birth—to determine the child’s age 

at the beginning of the 1998–99 school year. For 

first-time kindergartners (i.e., those who entered 

on time or who experienced a delayed entry), 

this variable refers to their age at entry into 

kindergarten. For children repeating 

kindergarten, this variable refers to their age at 

the start of their second year of kindergarten. 

The month and year of birth variables were 

combined to form five categories: children age 4 

 

16Independent information collected from parents during the 

kindergarten year children’s teachers provided information on their 

classrooms. One of the pieces of information the teacher provided 

was a description of the classroom in terms of grade. Teachers 

could indicate whether the classroom was a regular kindergarten 

classroom, the first year of a two-year kindergarten program, the 

second year of a two-year kindergarten program, transitional 

kindergarten, transitional first grade, ungraded class, and/or 

multigraded class. This report relied on parent information and did 

not include or exclude children from certain definitions the parent 

provided based on the teacher’s description of the classroom. In 

terms of the analytic sample used in this report, of the 12,495 

children, about 82 children (unweighted) were classified by the 

teacher as attending a transitional kindergarten program (first year 

of a two year program; second year of a two year program; a 

transitional program) or a transitional first grade program. Of these 

82 children, 25 were classified by their parents as being retained, 7 

as delayed, and 50 as on time. 

years, 8 months through 4 years, 11 months 

(born September–December 1993) when they 

entered kindergarten; children age 5 years, 0 

months through 5 years, 3 months (born May–

August 1993) when they entered kindergarten; 

children age 5 years, 4 months through 5 years, 

7 months (born January–April 1993); children 

age 5 years, 8 months through 5 years, 11 

months (born September–December 1992); and 

children age 6 years, 0 months through 6 years, 

7 months (born January 1992–August 1992). 

When deriving this variable, September 1, 1998 

was assumed to be the school start date for all 

children. [variable derived for this report, not 

presented on data file] 

Children’s race/ethnicity. The race/ethnicity 

composite (RACE) was constructed from two 

parent-reported variables: ethnicity and race. 

New Office of Management and Budget 

guidelines (1997) were followed under which a 

respondent could select more than one race. 

Thus, each respondent had to identify whether 

the child was Hispanic, and then select one or 

more races. The following are the five 

composite race/ethnicity categories presented in 

this report: White non-Hispanic, Black nonHispanic, Hispanic, Asian, and Other (which 

includes Pacific Islanders, American Indians, 

Alaska Natives, and multiracial children). When 

race/ethnicity differences are presented in this 

report, White refers to White, non-Hispanic and 

Black refers to Black, non-Hispanic. Each child 

belongs to only one of these five categories. 

[variable derived for this report, not presented 

on data file] 

Developmental difficulty. The variable used in 

this report is based on the recommended revision 

of the ECLS-K P4DISABL composite variable 

presented on the file. It was derived from 

information collected in the Child Health and 

Well-Being section of the spring first grade 

parent interview. Questions in the parent 

interview asked about the child’s ability to pay 

attention and learn, overall activity level, ability 

to communicate, difficulty hearing and 

understanding speech, and eyesight if not 

correctable with eyeglasses. For each condition, 

a question was asked about whether a diagnosis 

was obtained. Additionally, a question was also 
13

asked about receipt of therapy services. The 

composite variable was coded 1 (Yes) if any of 

the diagnosis variables or therapy services were 

coded 1 (Yes). [variable derived for this report, 

not presented on data file] 

Poverty status. In this report, poverty status 

reflects being below the federal poverty 

threshold in both the kindergarten (WKPOV_R) 

and first grade (W1POVRTY) years. The 

poverty variables were created using household 

income and family size. Income was compared 

to Census poverty thresholds, which vary by 

household size. Households whose income fell 

below the appropriate threshold were classified 

as poor. The thresholds in the kindergarten year 

were based on 1998 Census information, where 

a household of four with a total household 

income below $16,655 was considered to be in 

poverty. The thresholds in the first-grade year 

were based on 1999 Census information, where 

a household of four with a total household 

income below $17,029 was considered to be in 

poverty. If children were living below the 

federal poverty threshold in both kindergarten 

(WKPOV_R=1) and first grade 

(W1POVRTY=1), their poverty status was 

defined as below poverty threshold. If children 

were living at or above the threshold at either 

kindergarten or first grade or at both rounds, 

children’s poverty status was defined as at or 

above poverty threshold. [variable derived for 

this report, not presented on the data file] 

Parental education. This variable was 

constructed using the questions on the highest 

grade the child’s mother or female guardian or 

father or male guardian had completed, and 

whether the mother or female guardian or father 

or male guardian had obtained a high school 

equivalency degree if he or she did not complete 

high school. This report uses the data gathered 

during the kindergarten year as analyses 

included children’s achievement during the 

kindergarten year. This information was 

collapsed into four categories: less than high 

school, high school or equivalent, some college 

including vocational/technical training, and 

bachelor’s degree or higher. [WKPARED] 

Preschool experience. This variable was 

created through information in the fall 

kindergarten Child Care section of the parent 

interview. Preschool experience was defined as 

children’s participation in either a center-based 

arrangement or Head Start program in the year 

prior to kindergarten. The preschool experience 

variable was coded yes if either one or both of 

the child care variables (P1CPREK, 

P1HSPREK) were yes (1). [variable derived for 

this report, not presented on data file]

Fall 1998 kindergarten program type. This 

report refers to two types of kindergarten 

programs: full-day (or all day) and half-day (AM 

only or PM only). This variable was created 

using two composites that collected information 

on class type (AM, PM, or all-day). One 

composite derived class type from the fall 

kindergarten teacher questionnaire part A 

(A1CLASS). A second composite derived class 

type from the field management system that was 

used by field staff to schedule in-school child 

assessments (F1CLASS). Fall kindergarten 

program type was coded full-day if A1CLASS 

was 3 (all-day kindergarten) and was coded halfday if A1CLASS was 1 or 2 (AM or PM 

kindergarten). If A1CLASS was missing for a 

child, then F1CLASS was used to code fall 

kindergarten program type. If A1CLASS was 

missing and F1CLASS was 3 (all-day), 

kindergarten program type was coded full-day. 

If A1CLASS was missing and F1CLASS was 1 

or 2 (AM or PM), kindergarten program type 

was coded half-day. [variable derived for this 

report, not presented on data file] 

Acknowledgments 

The authors thank the following individuals for 

their thoughtful reviews and suggestions that 

greatly improved the quality of this report: 

Rachel Dinkes, Jed Tank, and Kevin Bromer of 

the American Institutes for Research (AIR); 

Marilyn Seastrom, Shelley Burns, and Bill 

Hussar from the National Center for Education 

Statistics (NCES), and Anne Ricciuti from the 

Institute of Education Sciences (IES), U.S. 

Department of Education; and two anonymous 

reviewers. 
14

For More Information 

For more information about this Statistics in 

Brief or the data set, contact Elvira Germino 

Hausken, ECLS-K Project Officer, National 

Center for Education Statistics, 1990 K Street 

NW, Washington, DC 20006-5651; e-mail 

elvira.hausken@ed.gov; or visit the ECLS 

website (http://nces.ed.gov/ecls).

References 

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21/2921.pdf 

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16 

Table 1. Percent of children, by 1998 kindergarten enrollment status, child, family, and school characteristics: Fall 

1998 

Characteristic All children On-time entry Repeated1 Delayed entry 

Sex 

 Male 51 49 66 60 

 Female 49 51 34 40 

 

Age at kindergarten entry (fall 1998) 

 4 yrs, 8 mos – 4 yrs, 11 mos 7 2 3 2 

 5 yrs, 0 mos – 5 yrs, 3 mos 31 24 4 5 

 5 yrs, 4 mos – 5 yrs, 7 mos 31 33 10 10 

 5 yrs, 8 mos – 5 yrs, 11 mos 25 34 32 47 

 6 yrs, 0 mos – 6 yrs, 7 mos 6 7 51 36 

 

Race/ethnicity 

 White, non-Hispanic 64 64 61 72 

 Black, non-Hispanic 17 17 19 14 

 Hispanic 13 13 14 9 

 Asian 2 2 1 2 

 Other 4 4 5 3 

 

Developmental difficulty2

 

 No 90 91 78 87 

 Yes 10 9 22 13 

 

Family poverty status3

 

 Not below poverty threshold 88 89 81 89 

 Below poverty threshold 12 11 19 11 

 

Highest parental education 

 Less than high school 7 7 17 6 

 High school diploma/GED 27 27 24 21 

 Some college, including vocational-technical 34 35 33 34 

 Bachelors’ or higher 31 31 26 38 

 

Preschool experience4 

 Yes 71 71 63 65 

 No 29 29 37 35 

 

Fall 1998 kindergarten program type 

 Half-day 44 44 27 51 

 Full-day 56 56 73 49 

1

For children who repeated kindergarten in the 1998-99 school year, estimates for age of school entry and kindergarten program type are 

for the year they repeated kindergarten, not their first year in kindergarten. 2

A child with a developmental difficulty is defined as one whose parents noted by first grade obtaining a diagnosis from a professional for 

problems related to attention, activity, communication, hearing, or sight that could not be corrected with eyeglasses. 3

Poverty status here refers to the child’s family status for both kindergarten and first grade. Below poverty threshold includes children 

whose family household income is below the federal poverty threshold in both the kindergarten and first-grade years. 4

Preschool experience was defined by children’s attendance in either a center-based arrangement or in Head Start during the year prior to 

kindergarten. 

NOTE: Estimates are for kindergartners from the 1998–99 school year who did not enter school early that year and who were promoted to 

first grade. Estimates are based on only those children who were given the ECLS-K direct cognitive assessment in English. Details may 

not sum to totals because of rounding. 

SOURCE: U.S. Department of Education, National Center for Education Statistics, Early Childhood Longitudinal Study, Kindergarten 

Class of 1998-99, (ECLS-K), Longitudinal Kindergarten-First Grade Public-Use Data File. 
17 

Table 1a. Standard errors for the percent of children, by 1998 kindergarten enrollment status, child, family, and 

school characteristics: Fall 1998 

Characteristic All children On-time entry Repeated1

 Delayed entry 

Sex 

 Male 0.5 0.6 2.8 2.6 

 Female 0.5 0.6 2.8 2.6 

 

Age at kindergarten entry (fall 1998) 

 4 yrs, 8 mos – 4 yrs, 11 mos 0.6 0.6 1.7 .6 

 5 yrs, 0 mos – 5 yrs, 3 mos 0.5 0.6 1.3 1.1 

 5 yrs, 4 mos – 5 yrs, 7 mos 0.7 0.7 1.9 1.2 

 5 yrs, 8 mos – 5 yrs, 11 mos 0.7 0.8 2.6 2.5 

 6 yrs, 0 mos – 6 yrs, 7 mos 0.4 0.2 3.9 2.3 

 

Race/ethnicity 

 White, non-Hispanic 1.4 1.5 3.7 2.4 

 Black, non-Hispanic 0.9 1.0 2.8 1.8 

 Hispanic 0.9 0.9 2.2 1.5 

 Asian 0.2 0.2 0.4 0.5 

 Other 0.7 0.6 1.9 1.1 

 

Developmental difficulty2

 

 No 0.4 0.5 2.4 1.4 

 Yes 0.4 0.5 2.4 1.4 

 

Family poverty status3

 

 Not below poverty threshold 0.8 0.8 2.9 1.4 

 Below poverty threshold 0.8 0.8 2.9 1.4 

 

Highest parental education 

 Less than high school 0.4 0.5 2.4 1.4 

 High school diploma/GED 0.8 0.9 2.4 1.9 

 Some college, including vocational-technical 0.7 0.8 2.8 2.4 

 Bachelors’ or higher 1.0 1.0 3.7 2.3 

 

Preschool experience4 

 Yes 0.9 1.0 2.8 2.6 

 No 0.9 1.0 2.8 2.6 

 

Fall 1998 kindergarten program type 

 Half-day 2.7 2.7 4.3 3.2 

 Full-day 2.7 2.7 4.3 3.2 

1

For children who repeated kindergarten in the 1998-99 school year, estimates for age of school entry and kindergarten program type are 

for the year they repeated kindergarten, not their first year in kindergarten. 2

A child with a developmental difficulty is defined as one whose parents noted by first grade obtaining a diagnosis from a professional for 

problems related to attention, activity, communication, hearing, or sight that could not be corrected with eyeglasses. 3

Poverty status here refers to the child’s family status for both kindergarten and first grade. Below poverty threshold includes children 

whose family household income is below the federal poverty threshold in both the kindergarten and first-grade years. 4

Preschool experience was defined by children’s attendance in either a center-based arrangement or in Head Start during the year prior to 

kindergarten. 

NOTE: Estimates are for kindergartners from the 1998–99 school year who did not enter school early that year and who were promoted to 

first grade. Estimates are based on only those children who were given the ECLS-K direct cognitive assessment in English. Details may 

not sum to totals because of rounding. 

SOURCE: U.S. Department of Education, National Center for Education Statistics, Early Childhood Longitudinal Study, Kindergarten 

Class of 1998-99, (ECLS-K), Longitudinal Kindergarten-First Grade Public-Use Data File. 
18 

Table 2. Children’s mean scale scores and percentage demonstrating specific reading and mathematics knowledge 

and skills in spring first grade, by 1998 kindergarten enrollment status: Spring 2000 

Characteristic All children On-time entry Repeated Delayed entry 

Reading, fall kindergarten 

 Mean overall scale score 23 23 25 24 

 

Mathematics, fall kindergarten 

 Mean overall scale score 20 20 21 23 

Reading, spring first grade 

 Mean overall scale score 57 57 52 59 

 Percentage demonstrating specific 

 reading knowledge and skills 

 Ending sounds 94 94 88 95 

 Sight words 82 82 68 85 

 Words in context 47 47 33 51 

 

Mathematics, spring first grade 

 Mean overall scale score 44 44 42 46 

 Percentage demonstrating specific 

 mathematics knowledge and skills 

 Ordinality 95 96 92 97 

 Addition and subtraction 76 76 69 80 

 Multiplication and division 27 27 23 34 

NOTE: Estimates are for kindergartners from the 1998–99 school year who did not enter school early that year and who were 

promoted to first grade. Estimates are based on only those children who were given the ECLS-K direct cognitive assessment in 

English. Details may not sum to totals because of rounding. 

SOURCE: U.S. Department of Education, National Center for Education Statistics, Early Childhood Longitudinal Study, Kindergarten 

Class of 1998-99, (ECLS-K), Longitudinal Kindergarten-First Grade Public-Use Data File. 
19 

Table 2a. Standard errors for children’s mean scale scores and percentage demonstrating specific reading and 

mathematics knowledge and skills, by 1998 kindergarten enrollment status: Spring 2000 

Characteristic All children On-time entry Repeated Delayed entry 

Reading, fall kindergarten 

 Mean overall scale score 0.2 0.2 0.9 0.4 

 

Mathematics, fall kindergarten 

 Mean overall scale score 0.1 0.2 0.6 0.4 

Reading, spring first grade 

 Mean overall scale score 0.3 0.3 1.1 0.7 

 Percentage demonstrating specific 

 reading knowledge and skills 

 Ending sounds 0.3 0.3 1.3 0.6 

 Sight words 0.6 0.7 2.4 1.2 

 Words in context 0.9 0.9 3.2 2.0 

 

Mathematics, spring first grade 

 Mean overall scale score 0.2 0.2 0.7 0.3 

 Percentage demonstrating specific 

 mathematics knowledge and skills 

 Ordinality 0.3 0.3 1.2 0.5 

 Addition and subtraction 0.7 0.7 2.3 1.1 

 Multiplication and division 0.8 0.8 2.3 2.0 

NOTE: Estimates are for kindergartners from the 1998–99 school year who did not enter school early that year and who were 

promoted to first grade. Estimates are based on only those children who were given the ECLS-K direct cognitive assessment in 

English. Details may not sum to totals because of rounding. 

SOURCE: U.S. Department of Education, National Center for Education Statistics, Early Childhood Longitudinal Study, Kindergarten 

Class of 1998-99, (ECLS-K), Longitudinal Kindergarten-First Grade Public-Use Data File. 
20 

Table 3. Least squares estimates of child characteristics, family characteristics, school experiences, and 1998 kindergarten 

enrollment status on first grade reading knowledge and skills: Fall 1998 and spring 2000 

Overall 

reading scale score Ending sounds Sight words 

Words in 

context 

B SE B SE B SE B SE 

Intercept 34.20* 0.86 82.90* 1.29 52.49* 2.92 -19.65* 2.87 

 

Fall 1998 reading scale score 0.86* 0.02 0.37* 0.02 1.13* 0.05 2.42* 0.06 

Sex (Male) 

 Female 0.66* 0.26 1.39* 0.31 3.39* 0.72 1.50* 0.90 

Age at 1998 kindergarten entry 0.08* 0.15 -0.24* 0.18 -0.65* 0.41 0.65* 0.52 

Race/ethnicity (White) 

 Black, non-Hispanic -2.68* 0.45 -3.06* 0.59 -7.75* 1.51 -6.18* 1.44 

 Hispanic 0.36* 0.52 0.17* 0.55 -1.66* 1.42 1.77* 1.86 

 Asian -0.05* 0.65 -1.12* 0.61 -3.55* 1.82 0.40* 2.29 

 Other, non-Hispanic -1.85* 0.78 -3.40* 1.61 -6.86* 3.01 -4.79* 2.06 

 

Developmental difficulty (No)1 

 Yes -4.23* 0.50 -6.34* 1.23 -12.93* 1.96 -10.85* 1.54 

 

Family poverty status (Not)2 

 Below poverty threshold -2.43* 0.49 -3.63* 0.81 -10.76* 1.66 -6.90* 1.46 

 

Parent education 1.41* 0.17 1.55* 0.21 -9.61* 0.53 4.26* 0.54 

Preschool experience (Yes) 3 

 No -0.55* 0.31 0.21* 0.42 0.38* 0.97 -2.30* 0.79 

 

Fall 1998 kindergarten program 

 type (Half-day) 

 Full-day 0.19* 0.39 0.01* 0.35 -0.14* 0.85 1.17* 1.34 

Enrollment status (On time) 

 Repeated kindergarten -5.21* 0.51 -4.55* 1.06 -13.14* 2.10 -13.79* 2.19 

 Delayed kindergarten entry 0.27* 0.46 0.06* 0.62 -0.30* 1.46 0.79* 1.94 

*p<.05. 

† Not applicable. 

1

A child with a developmental difficulty is defined as one whose parents noted by first grade obtaining a diagnosis from a professional for problems 

related to attention, activity, communication, hearing, or sight that could not be corrected with eyeglasses. 2

Below poverty threshold includes children whose family household income is below the federal poverty threshold in both the kindergarten and firstgrade years. 

3

Preschool experience was defined by children’s attendance in either a center-based arrangement or in Head Start during the year prior to kindergarten. 

NOTE: In this analysis, the overall ECLS-K kindergarten and first-grade reading scale score has a potential range of 0 to 92. The spring first grade 

proficiency probabilities Ending Sounds, Sight Words, and Words in Context have a potential range of 0 to 100. For categorical variables, the omitted 

category is presented in parenthesis in the row headers. B is the unstandardized regression coefficient. SE is the standard error of B (the unstandardized 

regression coefficient). Data are for kindergartners from the 1998–99 school year who did not enter school early that year and who were promoted to 

first grade. Estimates are based on only those children who were given the ECLS-K direct cognitive assessment in English. 

SOURCE: U.S. Department of Education, National Center for Education Statistics, Early Childhood Longitudinal Study, Kindergarten Class of 1998-

99, (ECLS-K), Longitudinal Kindergarten-First Grade Public-Use Data File. 
21 

Table 4. Least squares estimates of child characteristics, family characteristics, school experiences, and 1998 

kindergarten enrollment status on first grade mathematics knowledge and skills: Fall 1998 and spring 

2000 

Overall 

mathematics 

scale score Ordinality 

Addition and 

subtraction 

Multiplication 

and 

division 

B SE B SE B SE B SE 

Intercept 23.12* 0.60 83.80* 1.13 33.43* 2.29 -34.64* 2.35 

 

Fall 1998 reading scale score 0.72* 0.02 0.53* 0.04 1.99* 0.07 2.96* 0.05 

Sex (Male) 

 Female -0.69* 0.14 0.23* 0.32 -0.25* 0.58 -5.38* 0.54 

Age at 1998 kindergarten entry -0.12* 0.09 -0.20* 0.17 -0.51* 0.31 -0.22* 0.36 

Race/ethnicity (White) 

 Black, non-Hispanic -2.85* 0.30 -2.74* 0.79 -10.29* 1.37 -8.89* 0.95 

 Hispanic -0.43* 0.31 -0.14* 0.84 -1.20* 1.18 -2.18* 1.12 

 Asian -1.75* 0.51 -1.83* 0.68 -7.73* 2.44 -4.54* 1.73 

 Other, non-Hispanic -1.53* 0.38 -1.45* 0.82 -6.83* 1.65 -3.58* 1.26 

 

Developmental difficulty (No)1 

 Yes -2.28* 0.39 -5.52* 0.97 -9.65* 1.51 -2.40* 1.12 

 

Family poverty status (Not)2 

 Below poverty threshold -0.61* 0.30 -1.67* 0.85 -3.91* 1.40 0.84* 0.71 

 

Parent education 0.89* 0.08 0.94* 0.18 2.74* 0.35 3.11* 0.35 

Preschool experience (Yes) 3 

 No -0.30* 0.18 -0.21* 0.44 -0.68* 0.70 -1.52* 0.78 

 

Fall 1998 kindergarten program 

 type (Half-day) 

 Full-day 0.26* 0.25 0.83* 0.43 1.26* 0.76 -0.12* 1.09 

 

Enrollment status (On time) 

 Repeated kindergarten -1.94* 0.43 -2.68* 1.04 -6.95* 1.80 -4.85* 1.55 

 Delayed kindergarten entry -0.75* 0.26 -0.33* 0.46 -2.46* 1.03 -2.67* 1.32 

*p<.05. 

† Not applicable. 

1

A child with a developmental difficulty is defined as one whose parents noted by first grade obtaining a diagnosis from a professional for problems 

related to attention, activity, communication, hearing, or sight that could not be corrected with eyeglasses. 2

Below poverty threshold includes children whose family household income is below the federal poverty threshold in both the kindergarten and firstgrade years. 

3

Preschool experience was defined by children’s attendance in either a center-based arrangement or in Head Start during the year prior to kindergarten. 

NOTE: In this analysis, the overall ECLS-K kindergarten and first-grade mathematics scale score has a potential range of 0 to 64. The spring first 

grade proficiency probabilities Ordinality, Addition and Subtraction, and Multiplication and Division have a potential range of 0 to 100. For categorical 

variables, the omitted category is presented in parenthesis in the row headers. B is the unstandardized regression coefficient. SE is the standard error of 

B (the unstandardized regression coefficient). Data are for kindergartners from the 1998–99 school year who did not enter school early that year and 

who were promoted to first grade. Estimates are based on only those children who were given the ECLS-K direct cognitive assessment in English. 

SOURCE: U.S. Department of Education, National Center for Education Statistics, Early Childhood Longitudinal Study, Kindergarten Class of 1998-

99, (ECLS-K), Longitudinal Kindergarten-First Grade Public-Use Data File.