Employment: An Introduction

The employer roster: How the event history data collection process works

The remainder of the section consists of a detailed example of how the Event History data collection process works.

Employer Roster Creation in Round 1

Raw data collection: The round 1 survey asked for the names of all employers for whom the respondent had worked since age 14. Assume that a respondent named Emma reported delivering the Smalltown Press when she was 14, then switching companies and delivering the County Register, and finally working in her parents' business, Peel's Corner Store, at the time of the round 1 interview. For this example, the newspaper delivery jobs are assumed to be employee jobs and not freelance-type work. The survey then assigned a unique identification number (UID) in the order the jobs were reported: 9701 for the Smalltown Press, 9702 for the County Register, and 9703 for Peel's Store.

Roster creation and roster sort: After the UIDs were assigned, Emma reported the dates she started and stopped working for each employer. At this point, the survey program sorted the jobs according to stop date, so that the most recent employer was employer #01, the next most recent was employer #02, and so on. Therefore, Peel's Store (UID 9703) became job #01 on the roster, the County Register (UID 9702) was listed as job #02, and the Smalltown Press (UID 9701) was listed third. Key information about each employer, including the unique ID number and dates of employment, was organized in the employer roster. All of the information about Peel's Store is located in variables numbered #01 in the title, the County Register data are in variables numbered #02, and so on.

Example: Emma's Round 1 YEMP Roster

Employer UID Round 1 Roster Line #
Smalltown Press 9701 03
County Register 9702 02
Peel's Store 9703 01

Roster use in the interview: Throughout the rest of the employment section, the employer line numbers remain constant, so that each variable containing, for example, the phrase "Job #03" or "Employer #03" refers to Emma's Smalltown Press job. Note that the Smalltown Press is not the third employer Emma reported at the beginning of the employment section of the interview. It became employer #03 during the roster sort because the other two jobs were more recent.

Roster Creation in Round 2

Data from previous interviews: The employer information was collected in a similar manner in subsequent rounds. Because data were available from the previous interview, they could be used in the construction of the round 2 roster. Before the survey was fielded, survey staff loaded information about each respondent into the interviewers' laptops. In Emma's case, part of this information would be the list of employers she reported in round 1.

Raw data collection: During the survey, respondents first provided information about employers who were current at the last interview date. Assume that Emma stated that she worked at Peel's Store for several months after the round 1 interview. Respondents next reported new employers since the last interview date in no particular order. Emma reported only one additional job, waiting tables at Steed's Diner after she turned 16. At this point UIDs were given to each employer. Because Peel's Store was previously reported, it already had a UID--9703--assigned during the last interview. Steed's Diner was a new employer in round 2, so it was given a UID of 9801.

Roster creation and roster sort: Emma then reported the date she stopped working at each job, and the roster was sorted according to these stop dates. At the round 2 interview, the diner job was more recent, so it was listed as job #01 on the roster, and the store became job #02. At this point, the roster contains information from multiple survey rounds. The UID and start date of the Peel's Store job are carried over from round 1, while the stop date of the store job and all the information about Steed's Diner comes from round 2. Because Emma had not worked for the Smalltown Press or the County Register since the round 1 interview, neither of those employers is listed on the round 2 roster.

Example: Emma's Round 2 YEMP Roster

Employer UID Round 1 Roster Line # Round 2 Roster Line #
Peel's Store 9703 01 02
Steed's Diner 9801 -- 01

Roster use in the interview: Just as in round 1, the employer line numbers remain the same for the rest of the interview. As Emma answered questions about Steed's Diner, her rate of pay, hours worked, etc., were recorded in the "Employer #01" questions. Peel's Store data were recorded in the "Employer #2" series.

Roster Creation in Round 3 and Subsequent Surveys

Data from previous interviews: This was collected as it was in round 2. Information reported in previous rounds, including the list of employers previously reported, was loaded into interviewers' laptops before the survey was fielded.

Raw data collection: During her round 3 interview, Emma reported her ongoing employment at Steed's Diner, where she had been working in round 2. In addition, she went back to work at the Smalltown Press for a 6-month period in between interviews. Both employers retained their original UID numbers, 9801 for the diner and 9701 for the newspaper, despite the break in Emma's employment at the latter. 

Roster creation and roster sort: The roster is again sorted according to the stop date of each job. Since it is a current employer and does not yet have a stop date, Steed's Diner is listed as job #01 on the round 3 roster. The Smalltown Press becomes job #02 since Emma's employment there had stopped by the date of her round 3 interview. Previous jobs not reported in this round are not listed on this roster.

Example: Emma's Round 3 YEMP Roster

Employer UID Round 2 Roster Line # Round 3 Roster Line #
Steed's Diner 9801 01 01
Smalltown Press 9701 -- 02

Roster use in the interview: These employer line numbers are in place for the duration of the interview, just as in previous rounds. Information about her employment at the diner is recorded in "Employer #01" questions, while data about the newspaper are recorded in the "Employer #02" series.

Use of the Employer Roster in Analysis

Emma's information, as organized in the employer rosters, can be used to examine the characteristics of her jobs at the date of each interview or over time. This example focuses primarily on the round 2 employer roster, but subsequent rounds also follow the same sequence for forming the employer roster.

As described above, Emma worked for Peel's Store and Steed's Diner during the period between the round 1 and round 2 interviews. Information about these employers was sorted and a roster constructed with the most recent employer appearing first. A researcher using these data would need to be aware of the impact of roster construction.

Because the roster is sorted and employers reported in different rounds may be mixed, variables with "Employer #01" in the title do not necessarily refer to employer number 9701, 9801, etc. The #01 refers solely to the order of the job as listed on the current year's roster. The unique identification numbers provide a crosswalk between the two systems of identification. The UIDs also allow users to link employers across survey rounds and to identify the round in which an employer was first reported.

For example, Emma's value for the round 2 variable R24761., "YEMP, Employer 02 Unique ID (Ros Item)," would be 9703--Peel's Store. The user can identify this as an ID assigned in round 1 because it starts with "97," and look at the round 1 UID variables (R05311.-R05317.) to match the employer. In Emma's case, the comparable variable for employer #01 in round 1 would have UID 9703. Therefore, the researcher knows that information about employer #01 in round 1 refers to the same job as variables about employer #02 in round 2. The variables from the two rounds can then be compared to determine if there were any changes in characteristics such as hours worked, rate of pay, occupation, etc.

The roster line numbers and UID variables in the event history data work in the same way. For example, a researcher might want to know Emma's employment status in the first and last week of 1998. In the first week of 1998 (variable EMP_STATUS_1998.01), Emma was working at her parents' store, so the status variable would have a value of 9703. Using this UID, researchers can link that job to all of the other information collected during the interview. For example, in the main round 2 data Peel's Store is job #02, according to variable YEMP_UID_1998.02 (R24761.). Similarly, for the final week of 1998 (variable EMP_STATUS_1998.01), when Emma was working at Steed's Diner, the status variable would have a value of 9801. The job with a UID of 9801 is employer #01 in round 2, so job characteristic data are contained in the employer #01 variables. The second set of event history variables, the start and stop dates of each job, uses the roster line numbers. For these variables, the number in the variable title refers to the same job as in the main data set. For example, the start and stop dates for Peel's Store in the event history data (variables EMP_START_WEEK_1998.02 and EMP_END_WEEK_1998.02) will also have #02 in the variable title.