# Can I use survival analysis to model employee attrition when employees have different start dates?

I have a dataset of a few thousand employees and want to compare time-to-terminate by their source of hire. The data is for a four year period. Out of the dataset about 15% have terminated, while the rest are still with the company.

I considered survival analysis but the employees started at many different times. Is there anyway to work around this? Or is there a more appropriate analysis?

Thanks!

EDIT: I found this paper which explains how to handle my problem of variable sample size: http://www.amstat.org/chapters/northeasternillinois/pastevents/presentations/summer05_Ibrahim_J.pdf

• Why do you think you have a problem at all? – shadowtalker Feb 7 '15 at 16:50
• Doesn't survival analysis require everyone to start at the same time, t0? Let's say I have data for the past two years and two groups of candidates: applied and recruited. In total there are 100 in the applied group and 150 in the recruited group, but starting at Feb 7 2013 (t0), only 10 applied and 15 recruited were working, with the others joining in the last two years. How do I include those who joined late than t0? – universltravlr Feb 7 '15 at 17:31
• – shadowtalker Feb 7 '15 at 19:52

• The technique isn't basing everything on the number of employees at $t_n$, if that's what you're afraid of. In your example, the fact that 10 employees are present at $t_0$ -- presumably hired before $t_0$ -- is more of a complicating factor than employees coming and going. – Wayne Feb 7 '15 at 20:38