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Table B-2.  Summary of SASS new teacher and BTLS nonresponse bias, by wave and nonresponse bias statistic: 2007–10
 
Nonresponse bias statistic 2007–08 SASS public school teachers with 1 to 3 years of experience Second wave without retrospective cases1 Second wave with retrospective cases1 Third wave Longitudinal without retrospective cases2 Longitudinal with retrospective cases2
Before nonresponse adjustment
Mean estimated percent relative bias -0.1 -2.0 -1.4 -1.9 -2.0 -2.6
Median estimated percent relative bias 0.2 -0.1 0.1 0.3 0.1 -0.5
Percent of variable categories significantly biased 0.0 6.8 9.0 9.9 7.7 9.9
After nonresponse adjustment
Mean estimated percent relative bias # -1.3 -1.1 -1.5 -1.3 -1.7
Median estimated percent relative bias 0.1 0.2 0.1 0.3 0.3 -0.1
Percent of variable categories significantly biased 4.6 2.7 6.3 5.9 5.4 6.3
# Rounds to zero.
1 Retrospective cases are respondents that were non-interviews during the second wave, but provided replies to second wave items during the third wave.
2 Longitudinal cases are those that responded to all three waves. Longitudinal retrospective cases responded to the first and third waves at the time of data collection, but provided replies to second wave items during the third wave.
SOURCE: U.S. Department of Education, National Center for Education Statistics, School Schools and Staffing Survey (SASS), "Public School Sample File" and "Public School Teacher Documentation File," 2007–08 and Beginning Teacher Longitudinal Survey(BTLS), First, Second and Third Waves Documentation Data File," 2007–10.