To obtain a sample of persons beginning temporary work, we select all workers in temporary work (SIC 736) from each month who were not in temporary work in the previous month. The sample is limited to workers between ages 18 and 45. Only those temporary workers whose employment begins at least 12 months before the last month of a panel are included in the analysis, as this allows us to observe outcomes one year later.(68) We include all spells of temporary employment, including multiple spells from the same individual, in our analysis and adjust our model standard errors for correlations among the observations.
This group of temporary workers is further divided into two groups. Prior to entering a temporary job, a person is either employed in nontemporary work or not employed. Since we believe that these two groups may be entering temporary jobs for different reasons, we divide the temporary worker groups into two groups. Treatment Group 1 includes temporary workers who were working in nontemporary employment in the month prior to taking a temporary job. Treatment Group 2 includes temporary workers who were not working in the month prior to taking a temporary job (either unemployed or out of the labor force).
The comparison group contains data for all persons who are not observed in temporary work in any wave of the SIPP.(69) As with the treatment groups, this broad comparison group is divided into two groups. Comparison Group 1 includes persons who were working in the month prior. Comparison Group 2 includes persons who were not working in the month prior (either unemployed or out of the labor force). Thus, based on work status in the prior month, we have two comparison groups.
We further divide Comparison Groups 1 and 2 into two groups based on employment status in the current month, which allows us to estimate the effect of temporary work as compared with both nontemporary employment and nonemployment. Comparison Group 1 is divided into Comparison Group 1A--those employed in the current month--and Comparison Group 1B--those not employed in the current month. Likewise, Comparison Group 2 is divided into Comparison Group 2A--those employed in the current month--and Comparison Group 2B--those not employed in the current month.
In sum, we have the following six treatment and comparison groups:
|В||Prior Month||Current Month|
|Treatment Group1||Employed in Nontemporary Work||Employed in Temporary Work|
|Treatment Group 2||Not Employed|
|Comparison Group 1A||Employed in Nontemporary Work||Employed in Nontemporary Work|
|Comparison Group 1B||Not Employed|
|Comparison Group 2A||Not Employed||Employed in Nontemporary Work|
|Comparison Group 2B||Not Employed|