# Presentation: 766417

## Using Data fromthe NationalSurvey of Childrenwith Special Health Care Needs

**Centers for Disease Control and Prevention**
**National Center for Health Statistics**

- Stephen Blumberg
- Julian Luke

**Notes:**
Presented July 14, 2004 at the NCHS Data Users Conference, Washington, DC

## Preparing to Download the Data

- Create a directory on your hard drive that will be used to store the required data files and programs.
- Data files, programs, and format libraries will be stored here.

## Slide 3

## Slide 4

## Slide 5

## Slide 6

## Slide 7

## Slide 8

## Slide 9

## Downloading the Data

- SAS datasets and documentation are available at:
- 	http://www.cdc.gov/nchs/slaits.htm
- Join the SLAITS listserv to find out about updates

## Slide 11

## Slide 12

## Slide 13

## Slide 14

## Data Files

- Screener File
- Household File
- CSHCN Interview File
- Insurance Analysis File

## Screener File

- One record for each child
- N = 372,174
- Use for...
- Proportion of children with SHCN
- Demographic characteristics of CSHCN

- Variables include...
- CSHCN Screener
- Age
- Sex
- Race
- Ethnicity
- State of residence

## Household File

- One record for each household
- N = 196,888
- Use for...
- Proportion of households that include CSHCN
- Demographic characteristics of these households

- Variables include...
- Total number of CSHCN in household
- Household size
- Household income (relative to FPL)
- Metropolitan Statistical Area status
- State of residence

## CSHCN Interview File

- One record for each randomly selected CSHCN with completed interview
- N = 38,866
- Use for...
- Estimates of health and service use for CSHCN

- Variables include...
- Relationship of respondent to child
- Health status
- Access to care
- Experience with care
- Adequacy of care
- Health insurance
- Impact of the special health care need on the family

## Insurance Analysis File

- One record for each randomly selected child with completed insurance interview
- N = 215,162
- Use for...
- Estimates of health insurance coverage for all children

- Variables include...
- Demographics
- Insurance coverage
- For low-income uninsured children...
- Reason why
- Medicaid/SCHIP experience
- Some health measures

## Slide 20

## Slide 21

## Slide 22

## Slide 23

## Data File Type

- Data are stored on the website as compressed or zipped files.
- The smaller compressed files make downloading the files quicker.
- Once the files are downloaded, you will need to use another piece of software to uncompress the files.

## Slide 25

## Slide 26

## Slide 27

## Slide 28

## Supporting Documentation

- Documentation
- Survey Instrument
- Methodology Report
- Frequency Counts and Variable List
- SAS Input Files
- Sample SAS Programs

## Associating Formats with the Data Files

- There are four files needed to create and attach formats to the data files.  They are the following:
- Create_Master_Formats_Permanent.sas
- Attach_Formats-Household.sas
- Attach_Formats-Screener.sas
- Attach_Formats-Interview.sas

## Slide 35

## Slide 36

## Slide 37

## Slide 38

## Creating Formatted Permanent SAS Data Sets

- In addition to the four format files, you will need the following four files to create permanent SAS data sets.  They are the following:
- Household_Formats.sas
- Interview_Formats.sas
- Screener_Formats.sas
- Insurance_Formats.sas

## Slide 40

## Slide 41

## Slide 42

## Slide 43

## Slide 44

## Slide 45

## Slide 46

## Slide 47

## Slide 48

## Slide 49

## SAS procedure that creates variable listing by position in the data set

**SAS procedure that creates variable listing by position in the data set**

**SAS procedure that creates unweighted variable value counts**

## Slide 51

## Slide 52

## Key Variables

## Key Variables:CSHCN Status

- Name: NEEDTYPE
- Location: Screener file
- Levels: 1 = non-CSHCN, 2 = CSHCN
- Derived from: CSHCN Screener

## Key Variables:State of Residence

- Name: STATE
- Location: All files
- Levels: Separate numeric code for each state

## Key Variables:Age

- Name: AGE
- Location: Screener file
- Levels: Age in years
- 0 = Younger than one year
- Missing Data: Respondent did not know or refused to provide date of birth or age

## Key Variables:Sex

- Name: SEX
- Location: Screener file
- Levels: 1 = male, 2 = female

## Key Variables:Ethnicity

- Name: HISPANIC
- Location: Screener file
- Levels: 1 = Hispanic origin, 0 = no

## Confidentiality

- Section 308d of the Public Health Service Act (42 U.S.C. 242m):
- 	“No information...may be used for any purpose other than the purpose for which it was supplied...[and] may not be published or released...if the particular establishment or person supplying the information or described in it is identifiable.”
- Prohibits the release of sub-state identifiers or contextual information

## Key Variables:Race

- Name: RACER, RACENAAN, RACEASIA, RACE_HI
- Location: Screener file
- Levels:
- RACER = White, Black, Other, Multirace
- RACENAAN adds Native American/AK Native
- RACEASIA adds Asian
- RACE_HI adds Asian and Native Hawaiian / PI
- Only RACER can be used for national estimates

## Key Variables:Income

- Name: POVLEVEL
- Location: Household file
- Levels: 9 categories relative to the Federal Poverty Level
- Derived from: Total number of household members and household income value
- Missing Data: Total household members and/or household income were missing

## Key Variables:Urban/Rural Identifier

- Name: MSASTATR
- Location: Household file
- Levels: 1 = Yes, 0 = No
- Missing Data: MSASTATR was suppressed in 16 states to protect the confidentiality of participants

## Key Variables:Number of Children in HH

- Name: TOTKIDSR
- Location: Household file
- Note: This variable refers to the number of children from the household in the screener data file.  Due to suppression of some screener records from large households, this variable may be inaccurate for large households.

## Key Variables:For Merging Data Files

- Unique Household Identifier: IDNUMR
- Unique Child Identifier: IDNUMXR

## Slide 65

## Slide 66

## Slide 67

## Slide 68

## Slide 69

## Slide 70

## Slide 71

## Slide 72

## Create first data set and

**Create first data set and**
**keep only the variables you need**

## Then sort the data by the linking variable (IDNUMX / IDNUMXR)

**Then sort the data by the linking variable (IDNUMX / IDNUMXR)**

## Create second data set and

**Create second data set and**
**keep only the variables you need**

## Then sort the data by the linking variable (IDNUMX / IDNUMXR)

**Then sort the data by the linking variable (IDNUMX / IDNUMXR)**

## Finally, create merged data set using MERGE and BY commands

**Finally, create merged data set using MERGE and BY commands**

## Apply SAS FREQ procedure to create crosstab using variables from both data sets

**Apply SAS FREQ procedure to create crosstab using variables from both data sets**

## Slide 79

## Use Weighted Data

- Sampling weights to permit national and state-specific estimates of health characteristics
- Sampling weights are adjusted for potential non-response biases
- Sampling weights are adjusted to account for non-coverage of non-telephone households

## Three Weights

- Household weight (WEIGHT_H)
- Screener weight (WEIGHT_S)
- Interview weight (WEIGHT_I)
-  The same weights are used for national and state-level analyses.

## Three Weights:Household Weight

- Name: WEIGHT_H
- Location: Household file
- Unit of Analysis: Household
- Representative of: Households with children nationally and in each state

## Three Weights:Screener Weight

- Name: WEIGHT_S
- Location: Screener file
- Unit of Analysis: Child
- Representative of: Children nationally and in each state
- For use when: Data analyzed are from the screener and household files

## Three Weights:Interview Weight

- Name: WEIGHT_I
- Location: Interview and Insurance file
- Unit of Analysis: Child
- Representative of: When used with interview file, representative of CSHCN nationally and in each state.
- For use when: Data analyzed include variables that are not from the screener or household files

## Slide 85

## Slide 86

## Slide 87

## Slide 88

## Slide 89

## Slide 90

## Create data set and

**Create data set and**
**keep only the variables you need**

## Apply PROC FREQ procedure using the weight statement and the household weight

**Apply PROC FREQ procedure using the weight statement and the household weight**

## Slide 93

## Slide 94

## Variance Estimation

- Sample design involved clustering of children within households and stratification of household within states.
- Therefore, SUDAAN, STATA, or other such programs must be used to obtain estimates of variability and statistical significance.

## Sampling Variables

- Stratum: State (STATE)
- PSU: Household (IDNUMR)
- In SUDAAN...
- PROC ... DESIGN=WR;
- NEST STATE IDNUMR;
- WEIGHT WEIGHT_I;  *** Use appropriate weight*

## Slide 97

## Slide 98

## Slide 99

## Slide 100

## Slide 101

## Slide 102

## Create data set and

**Create data set and**
**keep only the variables you need**

## Then sort the data by the stratum and PSU variables

**Then sort the data by the stratum and PSU variables**

## Run PROC CROSSTAB with the appropriate design, nest, and weight statements

**Run PROC CROSSTAB with the appropriate design, nest, and weight statements**

## Slide 106

## http://www.cshcndata.org

## http://www.cshcndata.org

## http://www.cshcndata.org

## For more information...

- Stephen Blumberg or Julian Luke
- Centers for Disease Control and Prevention
- National Center for Health Statistics
- 3311 Toledo Road
- Hyattsville, Maryland  20782
- SBlumberg@cdc.gov
- jluke@cdc.gov