## Teacher and Leader E **va luation Systems** 

**For Data Collection Instruments**

**Impact E valuation of**  **Teacher and Leader E va**  **luation Systems**

**OMB Clearance Request For Data Collection Instruments** 

**U.S. Department of Education Contract No. ED** 

**Am erican Institutes**  

## Impact E **valuation of Teacher and Leader E**  **va luation Systems** 

**OMB Clearance Request For Data Collection Instruments**  **, Part B**

**October 19**  **, 2012**  **Prepared for: U.S. Department of Education**  **Contract No. ED -**  **IES -**  **11 -**  **C -**  **0066**

**Prepared by :**  **Am erican Institutes**  **for Research**

## Contents **Page**

B. Description of Statistical Methods

................................ ................................ .............................. 1 1. Respondent Universe and Sampling Methods

................................ ................................ ....... 1 2. Procedures for Data Collection

................................ ................................ .............................. 4 3. Procedures to Maximize Response Rates

................................ ................................ .............. 4 4. Pilot

- Testing Instruments

................................ ................................ ................................ ....... 5 5. Names of Statistical and Methodological Consultants and Data Collectors

.......................... 6 References

................................ ................................ ................................ ................................ ........ 7



### Exhibits Exhibit 1 . Sampling Design

................................ ................................ ................................ ............. 3 Exhibit 2 . MDES for Main Outcome Measures

................................ ................................ ............... 4 

### Ap **pendixes** Appendix A. Teacher Survey Appendix B. Principal Survey Appendix C. District Interview Appendix D. District Archival Records Collection ProtocolImpact Evaluation of Teacher and Leader Evaluation Systems



### B. **Description of Statistical Methods** The proposed study focuses on the leader evaluation s ys tem components that is consistent with current federal policy

. the study , we randoml y assign ed districts: a control group will continue using sy stem ; a treatment group will implement sy stem components, which includes feedback on instructional practice, principal leadership, and student growth. We will collect outcome data from both groups. average outcome levels in the control estimate of the outcome levels that would have been observed not received the treatment. Therefore, the difference in the average outcomes between the treatment schools and the control schools within the same district the treatment’s impact. This approach to impact anal ys is members of the treatment and the their actual participation in the treatment. Following this approach, we will assess the the evaluation s ys tem components control schools in average read ing and mathematics achievement which teachers at each school actually participate activities associated with the treatment. The for each district and then pooled across districts to create an average in a meta
- analy sis). The resulting intent being assigned to implemen t the study ’s impact of participating in those activities. I n some respects, these estimates mirror those likely to be observed in real

- world settings In the remainder of Part B, we address the follo procedures for data collection, procedures to maximize response rates, pilot instruments, and the names of statistical and methodological consultants and data collectors. 

### 1. Respondent Universe and AIR established the sample of participating districts as described in the first OMB submission for the TLES Study (OMB 1850 TL ES Study

does not employ

random sampling of districts or schools for the sake of generalizability , these districts were screened and recruited on the basis of required b y the study

design. In the first step, AI R analyze d extant data on state policy

. ineligible due to state initiatives in teacher and leader evaluation that would eliminate or reduce the service contrast in either 2012 Within the remaining 29 states, the Common Core Data from the U.S. Department of ( 2010) was then used to identify 457 districts that were of sufficient size. For a district to be eligible for the study , it was required to have at least schools. Impact Evaluation of Teacher and Leader Evaluation Systems

— 1 

### Description of Statistical Methods The proposed study focuses on the implementation and the impacts of a package of teacher and leader evaluation s ys tem components that is consistent with current federal policy

. ed 1 0

–2 4 schools to 2 groups in each of the 9 participating group will continue using the district’s current teache r and leader evaluation

implement the study’s package of teacher and leader evaluation includes feedback on instructional practice, principal leadership, and We will collect outcome data from both groups. Due to random assignment, t

control schools not receiving the treatment represent a relia that would have been observed in the treatment schools had they the treatment. Therefore, the difference in the average outcomes between the treatment schools and the control schools within the same district represent a reliable estimate of

to impact anal ys is is known as the “intent

- to
- treat” approach, in which all

the control groups are included in the impact analys is regardless of their actual participation in the treatment. Following this approach, we will assess the

components on student achievement b y comparing the treatment and ing and mathematics achievement , regardless of the extent to which teachers at each school actually participate d in the teacher and leader evaluation system activities associated with the treatment. The impacts of the treatme nt will be estimated separatel y for each district and then pooled across districts to create an average impact of the treatments ( analy sis). The resulting intent

- to
- treat estimates can be interpreted as the

t the study ’s teacher and leader evaluation system , rather than the activities. I

n some respects, these estimates mirror those likely to world settings

. In the remainder of Part B, we address the follo wing: respondent universe and sampling, procedures for data collection, procedures to maximize response rates, pilot

- testing

names of statistical and methodological consultants and data collectors. 

### 1. Respondent Universe and **Sampling Methods** AIR established the sample of participating districts with a multistep process approved b y OMB submission for the TLES Study (OMB 1850

- 0890). Because the TL ES Study

does not employ

random sampling of districts or schools for the sake of generalizability , these districts were screened and recruited on the basis of the characteristics d extant data on state policy

. A ll districts in 21 states were deemed ineligible due to state initiatives in teacher and leader evaluation that would eliminate or reduce

either 2012

– 13 or 2013

– 14. Within the remaining 29 states, the Common Core Data from the U.S. Department of 2010) was then used to identify 457 districts that were of sufficient size. For a district to be was required to have at least 10 schools, with at least 6 being elementary a package of teacher and leader evaluation s ys tem components that is consistent with current federal policy

. To conduct participating r and leader evaluation teacher and leader evaluation includes feedback on instructional practice, principal leadership, and random assignment, t he schools not receiving the treatment represent a relia ble

in the treatment schools had they the treatment. Therefore, the difference in the average outcomes between the represent a reliable estimate of treat” approach, in which all control groups are included in the impact analys is regardless of their actual participation in the treatment. Following this approach, we will assess the impacts of on student achievement b y comparing the treatment and the , regardless of the extent to in the teacher and leader evaluation system

nt will be estimated separatel y of the treatments ( as treat estimates can be interpreted as the impact of rather than the activities. I

n some respects, these estimates mirror those likely to wing: respondent universe and sampling, testing the names of statistical and methodological consultants and data collectors.
a multistep process approved b y OMB

0890). Because the TL ES Study

does not employ

random sampling of districts or schools for the sake of characteristics
ll districts in 21 states were deemed ineligible due to state initiatives in teacher and leader evaluation that would eliminate or reduce Within the remaining 29 states, the Common Core Data from the U.S. Department of Education 2010) was then used to identify 457 districts that were of sufficient size. For a district to be being elementaryImpact Evaluation of Teacher and Leader Evaluation Systems

Of the 457 districts, 100 expressed interest in speaking with us study team interviewed the district contact telepho ne using the screening protocol approved by OMB in May 2012. The screening protocol was used to determine the district’s eligibility to participate in the stud y, based on its intended evaluation sy stem practices for 2012 value

- added modeling. The following criteria were used in this determination:

 **Teacher evaluation system**

 The current classroom observation protocol used for evaluating teachers is not comparable to FFT or CLASS or is not implemented intensively (e.g., does not include comprehensive yearl y training from the provider of the protocol).

 Tenured teachers are obse who are identified as having performance issues may be observed more often.

 The current teacher evaluation system does not include a teacher effectiveness measure based on value

 **Leader evaluation system.** degree assessment tool.

 **Data system.** The current data sy stems include student assessment data and teacher student

- course ID linkages required for conducting value The screening process and subsequent recruitment conversations with interested districts in 19 site visits to eligible and interested districts. these districts, eligible schools were identifed through dialogue with district officials about competing intiatives and other barriers to school participation, and were made to the pri ncipals of the memoranda of understanding indicating their willingness to be randoml y assigned as part of the study

. The final sample include s 4 districts using FFT and participating district, the participating schools have been randomly assigned to one of two groups: (1) piloting the evaluation sy stem treatment group) and (2) continuing We anticipate approximately 21 mathematics and reading teachers per school, each teaching an average of 25 students, in a given academic y ear. Thus, the total universe of teachers will be about 2,940 ; the total universe of students will be about structure of the sampling design

.

Impact Evaluation of Teacher and Leader Evaluation Systems

— 2 100 expressed interest in speaking with us . For each of these districts, the study team interviewed the district contact as well as a district data/assessment expert via ne using the screening protocol approved by OMB in May 2012. The screening protocol was used to determine the district’s eligibility to participate in the stud y, based on its intended evaluation sy stem practices for 2012

– 13 and 2013

– 14 and the adequacy of its data sy stems for added modeling. The following criteria were used in this determination: **Teacher evaluation system .**  The current classroom observation protocol used for evaluating teachers is not comparable to FFT or CLASS or is not implemented intensively (e.g., does not include comprehensive yearl y training from the provider of the protocol). Tenured teachers are obse rved at most twice a year. Teachers on probation or teachers who are identified as having performance issues may be observed more often. The current teacher evaluation system does not include a teacher effectiveness measure based on value

- added modeling. **Leader evaluation system.** The current leader evaluation system is not using a 360

The current data sy stems include student assessment data and teacher course ID linkages required for conducting value

- added mod eling. The screening process and subsequent recruitment conversations with interested districts 19 site visits to eligible and interested districts. Nine districts agreed to participate. Within these districts, eligible schools were identifed through dialogue with district officials about competing intiatives and other barriers to school participation, and presentations about the study the eligible schools . A total of 140 schools in the memoranda of understanding indicating their willingness to be randoml y assigned as part of the districts using FFT and 5 districts using C LAS S. Within each participating district, the participating schools have been randomly assigned to one of two

evaluation sy stem components provided through TLES (i.e., treatment group) and (2) continuing with “business as usual” (i.e., the control group). We anticipate approximately 21 mathematics and reading teachers per school, each teaching an average of 25 students, in a given academic y ear. Thus, the total universe of teachers will be of students will be about 73,500

. ( See Exhibit 1 for the complete

. ) . For each of these districts, the

as well as a district data/assessment expert via ne using the screening protocol approved by OMB in May 2012. The screening protocol was used to determine the district’s eligibility to participate in the stud y, based on its intended its data sy stems for
The current classroom observation protocol used for evaluating teachers is not comparable to FFT or CLASS or is not implemented intensively (e.g., does not include comprehensive yearl y training from the provider of the protocol). rved at most twice a year. Teachers on probation or teachers who are identified as having performance issues may be observed more often. The current teacher evaluation system does not include a teacher effectiveness

The current leader evaluation system is not using a 360

- The current data sy stems include student assessment data and teacher

eling. The screening process and subsequent recruitment conversations with interested districts resulted districts agreed to participate. Within these districts, eligible schools were identifed through dialogue with district officials about presentations about the study . A total of 140 schools in the 9 districts signed memoranda of understanding indicating their willingness to be randoml y assigned as part of the

LAS S. Within each participating district, the participating schools have been randomly assigned to one of two TLES (i.e., the control group). We anticipate approximately 21 mathematics and reading teachers per school, each teaching an average of 25 students, in a given academic y ear. Thus, the total universe of teachers will be

Exhibit 1 for the completeImpact Evaluation of Teacher and Leader Evaluation Systems

**District Teacher** 

**Observation Instrument**  **Study**

**Group**
District 1 FFT Treatment Control District 2 FFT Treatment Control District 3 FFT Treatment Control District 4 FFT Treatment Control District 5 CLASS Treatment Control District 6 CLASS Treatment Control District 7 CLASS Treatment Control District 8 CLASS Treatment Control District 9 CLASS Treatment Control **Totals** To assess the statistical power of the stud y d esign, we anal ys is for group randomized trials (Schochet, 2008; Spy brook, Raudenbush, Congdon, & Martinez, 2009) to calculate the variance components and estimate effect sizes (MDES s ) for student achievement outcomes, mobility outcomes, and intermediate outcomes (i.e., decisions of key actors) as measured by the teacher survey . We derive assumptions the outcome measures that are between schools and between teachers within schools, the percentage of outcome variance explained by covariates, the number of districts and of schools per district, the number of teachers per school, the number of students per the number of teachers observed per school. we have calculated MDES ranges for our main outcome measures (Exhibit 2).

Impact Evaluation of Teacher and Leader Evaluation Systems

— 3 **Exhibit 1** 
**. Sampling**  **Design Number of**  **Schools (unit of randomization)**  **Number of Teachers**

**(based on estimate of 21**  **teachers per school) Number of Students in**  **study (based on estimate of 25 students per**  Treatment 5 105

6 126 Treatment 8 168

7 147 Treatment 12 252

12 252 Treatment 7 147

7 147 Treatment 9 189

9 189 Treatment 7 147

6 126 Treatment 11 231

11 231 Treatment 6 126

7 147 Treatment 5 105

5 105 **140** 2,940 assess the statistical power of the stud y d esign, we draw on recent literature on power anal ys is for group randomized trials (Schochet, 2008; Spy brook, Raudenbush, Congdon, & to calculate the variance components and estimate the minimum detectable ) for student achievement outcomes, teacher practice outcomes, intermediate outcomes (i.e., decisions of key actors) as measured by the assumptions from prio r studies about the proportion of the variance in the outcome measures that are between schools and between teachers within schools, the percentage of outcome variance explained by covariates, the number of districts and the number of teachers per school, the number of students per the number of teachers observed per school. To reflect both optimistic and cautious assumptions, ranges for our main outcome measures (Exhibit 2). **Number of Students in study (based on estimate of**  **25 students per teacher** **)** 2,625 3,150 4,200 3,675 6,300 6,300 3,675 3,675 4,725 4,725 3,675 3,150 5,775 5,775 3,150 3,675 2,625 2,625 73,500 draw on recent literature on power anal ys is for group randomized trials (Schochet, 2008; Spy brook, Raudenbush, Congdon, & the minimum detectable teacher practice outcomes, teacher intermediate outcomes (i.e., decisions of key actors) as measured by the proportion of the variance in the outcome measures that are between schools and between teachers within schools, the percentage of outcome variance explained by covariates, the number of districts and the number the number of teachers per school, the number of students per teacher , and

To reflect both optimistic and cautious assumptions,Impact Evaluation of Teacher and Leader Evaluation Systems **Exhibit Outcome Measure**  Student achievement Teacher practice Teacher mobility Intermediate outcomes as the teacher survey 

### 2. Procedures for Data Collection AIR p roject staff will manage data collection and ensur collection instruments for which Appendi x es A

–D . They

include the teacher survey, and the district archival records collection protocol, preced ing Part A of this submission. teachers responsible for reading or mathematics i survey will be administered online to all interview will be conducted via tele be sent via e

- mail to each study district. The timeline : 1. **January 2013.**  Student records, and t administration

. 2. **April**

**– May, 2013.**  Teacher and principals surveys, and district interviews. 3. **July**

**– September,**  **2013.** Student records, and t eacher and principal records for mobility analy ses 4. **January**

**– March,**  **2014.** T 5. **April**

**– May, 2014.**  Teacher and principals surveys, and district interviews. 6. **July**

**– September,**  **2014.** Student records, and t eacher and principal records for mobility 

### 3. Procedures to Maximize Response Rates Based on our extensive experience with administering survey s in a variety

of schools, districts, and states, including a recent Intensive Partnerships for Effective Teaching (I PS) study funded by the Bill & Melinda Gates Foundation, we anticipate the percent for the teacher and the principal survey s. We anti d istrict inte rviews and the archival records because it is the most recent example of teacher and principal the issue of evaluation s ystems. The IPS teacher survey

and 76 percent on the school leader survey

Impact Evaluation of Teacher and Leader Evaluation Systems

—4 **Exhibit 2** 
**. MDES for Main Outcome Measures**  **Outcome Measure MDES**  **(Optimistic —**  **Cautious)** 0.08

– 0.11 0.1 5

– 0.1 6 9.4

– 9.7 percent (based on 20% base mobility rate in control group) as measured by 0.18 

### 2. Procedures for Data Collection data collection and ensur e qualit y and timeliness. T for which clear ance is requested in this submission are included in . They include the teacher survey, the principal survey , the district interview, district archival records collection protocol, as summarized in the study description of this submission. The teacher survey will be admi nistered online to all teachers responsible for reading or mathematics i nstruction in any of Grades K

– 8 survey will be administered online to all the principals of the study schools. The district tele phone with each study district. Archival record mail to each study

district. The above data collections are specified in the following Student records, and t eacher and principal records for online survey Teacher and principals surveys, and district interviews. Student records, local teacher performance evaluation eacher and principal records for mobility analy ses . T eacher and principal records for online survey administration Teacher and principals surveys, and district interviews. Student records, local teacher performance evaluation eacher and principal records for mobility analy ses . 

### 3. Procedures to Maximize Response Rates Based on our extensive experience with administering survey s in a variety

of schools, districts, and states, including a recent Intensive Partnerships for Effective Teaching (I PS) study funded Gates Foundation, we anticipate the respo nse rate to be approximately 85 principal survey s. We anti ci pat e a 100 percent response archival records requests. We reference the I PS study in particular it is the most recent example of teacher and principal survey s conducted b y AIR

The IPS study achieved response rates of 81 percent on the school leader survey . However, because t he IPS survey s (based on 20% base mobility

qualit y and timeliness. T he data in this submission are included in

district interview, as summarized in the study description nistered online to all

8 . The principal study schools. The district Archival record requests will above data collections are specified in the following online survey Teacher and principals surveys, and district interviews. performance evaluation ratings , online survey

administration

. Teacher and principals surveys, and district interviews. performance evaluation ratings ,

Based on our extensive experience with administering survey s in a variety

of schools, districts, and states, including a recent Intensive Partnerships for Effective Teaching (I PS) study funded approximately

85 response rate for requests. We reference the I PS study in particular conducted b y AIR around percent on the he IPS survey sImpact Evaluation of Teacher and Leader Evaluation Systems

were longer than our proposed surveys by roughly 60 percent, we believe that our response rate approximations are appropriate estimates. The following procedures will be used to ensure high response rates:

 Obtaining high response rates depends in part on the quality of the instruments. will pilot and subsequently refine all instruments to ensure easily understandable, which data collection activities and thus increase response rates. information on procedures designed to

 Obtaining high response rates also depends in pa The teacher and principal surveys require an administration time of approximately 30 minutes. The district interview is restricted to 90 minutes, which is reasonable given that districts are highly

motivated to partic

 To further ensure a high response rate on the Web

- based administration. as necessary , and a hard

- copy pencil any respondent who requests one. Approximately will begin the process of survey follow about the survey . After 2 approximately

10

- day intervals. During the third call, we will offer to complete the questionnaire as a telephone interview. Using these procedures, the research team has extensive experience administering Web

 District coordinators employed b y the study will be responsible for maintaining contact with the respondents as well as garnering the support of school principals survey completion.

 The study will offer a social incentive to the data collections as part of a high information to the d istricts and

 Teacher survey

r espondents in both the treatm small amount of compensation in return for participating in This is to make them feel that we value their time and participation them to participate and increasing section 9, Pay

ment or Gifts. 

### 4. Pilot **- Testing Instruments**  The teacher and principal surveys will be than 10 respondents per instrument) and revised to ensure that the questions are simple as possible for the respondents to complete. P ilot test subjects will include teachers and principals treatment educators (e.g., participating in a pilot system while an existing evaluation sy stem is in place

. A think

- aloud, or cognitive lab respondent s will be a sked to complete the draft instrument, explain their thinking as they Impact Evaluation of Teacher and Leader Evaluation Systems

— 5 were longer than our proposed surveys by roughly 60 percent, we believe that our response rate approximations are appropriate estimates. The following procedures will be used to ensure high response rates: Obtaining high response rates depends in part on the quality of the instruments. will pilot and subsequently refine all instruments to ensure that they are user easily understandable, which will increase participants’ willingness to participate in the data collection activities and thus increase response rates. See the next section for information on procedures designed to ensure instrument quality

. Obtaining high response rates also depends in pa rt on the length of the instruments. The teacher and principal surveys require an administration time of approximately

The district interview is restricted to 90 minutes, which is reasonable given that districts are highly

motivated to partic ipate in the study

. To further ensure a high response rate on the teacher survey , AI R will not rely entirel y on based administration. AIR will conduct follow

- up activities with telephone prompts,

copy pencil

- and

- paper survey questionnaire will be mailed to any respondent who requests one. Approximately 2 weeks after the initial mailing, we will begin the process of survey follow

- up. We will send a letter reminding respondents 2 more weeks, we will imple ment a series of 3 follow day intervals. During the third call, we will offer to complete the questionnaire as a telephone interview. Using these procedures, the research team has extensive experience administering Web

- and e - mail

-based surveys with high response rates. coordinators employed b y the study will be responsible for maintaining contact respondents as well as garnering the support of school principals will offer a social incentive to the respondents by stressing the importance of the data collections as part of a high

- profile study that will provide much istricts and the schools. espondents in both the treatm ent and the control groups will receive a small amount of compensation in return for participating in the data collection activities. This is to make them feel that we value their time and participation , thus encouraging them to participate and increasing the response rate. For specific details, please see Part A

Gifts. 

### Testing Instruments The teacher and principal surveys will be pilot

- tested with small numbers of respondents (fewer than 10 respondents per instrument) and revised to ensure that the questions are as respondents to complete. teachers and principals wh o are in similar situations as the study ’s treatment educators (e.g., participating in a pilot system while an existing evaluation sy stem is in aloud, or cognitive lab , format will be used for p ilot testing, whereb y sked to complete the draft instrument, explain their thinking as they were longer than our proposed surveys by roughly 60 percent, we believe that our response rate

Obtaining high response rates depends in part on the quality of the instruments. The team they are user - friendl y and increase participants’ willingness to participate in the

See the next section for the length of the instruments. The teacher and principal surveys require an administration time of approximately

The district interview is restricted to 90 minutes, which is reasonable given will not rely

entirel y on up activities with telephone prompts, questionnaire will be mailed to weeks after the initial mailing, we up. We will send a letter reminding respondents follow

- up calls at day intervals. During the third call, we will offer to complete the questionnaire as a telephone interview. Using these procedures, the research team has based surveys with high response rates. coordinators employed b y the study will be responsible for maintaining contact respondents as well as garnering the support of school principals for encouraging respondents by

stressing the importance of profile study

that will provide much

- needed control groups will receive a data collection activities. thus encouraging For specific details, please see Part A

tested with small numbers of respondents (fewer as clear and o are in similar situations as the study ’s treatment educators (e.g., participating in a pilot system while an existing evaluation sy stem is in testing, whereb y the sked to complete the draft instrument, explain their thinking as theyImpact Evaluation of Teacher and Leader Evaluation Systems

constructed their responses, and identify the following:

 Questions or response options that are difficult to understand

 Questions in which none of the response options is an accurate description of respondent’s circumstance

 Questions that call for a single response but more than one of the options is an appropriate response

.  Terms that are not defined that should be defined

 Quest ions for which the information requested is unavailable 

### 5. Names of Statistical and Methodological Consultants **and Data Collectors** This project is being conducted by AIR Michael Garet is the principal investigator task leaders from AIR contributing to the study methods and data collection are Jinok Kim, Anja Kurki, and David Manzeske. Garet, Andrew Way

ne, David Manzeske project staff will carry

ou t the data

Impact Evaluation of Teacher and Leader Evaluation Systems

— 6 constructed their responses, and identify the following: or response options that are difficult to understand

. in which none of the response options is an accurate description of circumstance

. that call for a single response but more than one of the options is an that are not defined that should be defined

. for which the information requested is unavailable

. 

### 5. Names of Statistical and Methodological Consultants by AIR under contract to the U.S. Department of Education. investigator , and Andrew Way ne is the project director task leaders from AIR contributing to the study methods and data collection are Seth Brown, Jinok Kim, Anja Kurki, and David Manzeske. The instruments were developed by Michael Andrew Way

ne, David Manzeske , Seth Brown, and additional project staff at AIR

data collection activities

. in which none of the response options is an accurate description of a that call for a single response but more than one of the options is an

under contract to the U.S. Department of Education. project director . The senior

Seth Brown, The instruments were developed by Michael and additional project staff at AIR

. AI RImpact Evaluation of Teacher and Leader Evaluation Systems

Schochet, P. (2008). Statistical power for random assignment evaluations of education programs. Journal of Educational and Behavioral Statistics, 33 Spy brook, J., Raudenbush, S. W., Congdon, R., & Martinez, A. (2009). longitudinal and multilevel research: Documentation for the Optimal Design software. Ann Arbor: Univers ity

of Michigan.

Impact Evaluation of Teacher and Leader Evaluation Systems

— 7 

## References Schochet, P. (2008). Statistical power for random assignment evaluations of education programs. Journal of Educational and Behavioral Statistics, 33 (1), 62

– 87. Spy brook, J., Raudenbush, S. W., Congdon, R., & Martinez, A. (2009). Optimal design for longitudinal and multilevel research: Documentation for the Optimal Design software.

ity of Michigan. Schochet, P. (2008). Statistical power for random assignment evaluations of education programs.