# Completion Rates and Attrition

## Survey Completion Rates

Completion rates for the ALP are high, generally in the 70 percent range. These rates can vary by subgroup, how long a survey is kept in the field, the number of reminders sent, interview topic, survey length, the amount of the incentive, and other factors. The completion rate for a given survey is calculated by dividing the number of completed interviews by the number of panel members invited to take that survey. Most ALP members complete an interview within one week of receiving the invitation and almost all do so within two weeks.

## Panel Attrition

Once in the ALP, participants tend to remain indefinitely, leading to low attrition rates. Over the past decade, annual attrition rates of the ALP are in the range of 6 to 15%. To calculate attrition rates, we calculate the proportion of "active" panel members at a base period and compare it with a later time period. An "active" panel member has completed at least one survey in the past year as well as updated her/his demographic information within the past year.

Mathematically, the attrition rate is the difference between (a) and (b) divided by (a), or (a-b)/a. ALP attrition rates by year since 2006 are in the last column of the table below.

Base Period Comparison Period Active in Base Period Active in Comparison Period Percentage Active Percentage Attrition
2006 2007 341 290 85.0 15.0
2007 2008 1332 1183 88.8 11.2
2008 2009 2473 2307 93.3 6.7
2009 2010 3138 2947 93.9 6.1
2010 2011 3207 2952 92.1 8.0
2011 2012 3231 2817 87.2 12.8
2012 2013 5449 4988 91.5 8.5
2013 2014 5875 5285 90.0 10.04

This table shows attrition for 2006 in 2007 was 15 percent. That is, of the 341 active respondents in 2006, 51 (or 341 less 290), or 15 percent, were no longer active in 2007. Similarly, it shows an attrition rate of 11 percent for 2007 respondents in 2008. The attrition rates have been between 6 and 15 percent annually.

Panel members generally do not give notice about their intent to leave the panel; rather, they simply stop participating in surveys. To avoid retention of disinterested panel members, RAND periodically attempts to contact members who have not been active for more than a year and removes from the panel those who no longer wish to take part or cannot be contacted.