The recent lifting of Department of Defense (DOD) combat exclusion provisions has prompted the Marine Corps to consider administering physical fitness tests before Marines are classified into physically demanding Military Occupational Specialties (MOSs). Since this classification process starts in the Delayed Entry Program (DEP), the Marine Corps needs to know whether the Initial Strength Test (IST) administered in the DEP can be used to classify recruits into Programs Enlisted For (PEFs) that contain physically demanding MOSs. Central to answering this question is whether IST scores are reliable predictors of attrition, injuries during recruit training, and in-service physical fitness. To assist the Marine Corps with early classification of recruits into physically demanding MOSs, this paper explores the relationships between DEP IST scores and attrition, injuries during recruit training, and in-service physical fitness.
Since the Marine Corps is considering using the IST as a criterion for PEF assignment, we selected the first IST score recorded in the DEP, since the timing would generally coincide with assignment of a recruit’s PEF. Recruiters try to assign PEFs to recruits as early as possible once they are in the DEP, so we chose the first IST recorded in the DEP to facilitate our analysis. For the DEP IST score, we combined the three separate IST events—the 1.5-mile run, pull-ups/flexed-arm hang (FAH), and crunches—to create a composite score that, as we explain later in this report, closely mirrors the scoring procedure for the Physical Fitness Test (PFT). We then measured the relationship between this composite DEP IST score and attrition rates, injury rates while in recruit training, and various PFT and Combat Fitness Test (CFT) scores taken during a Marine’s initial enlistment.
DEP IST score and attrition rates
Table 1 summarizes the relationship that we found between the DEP IST score and attrition during three key time periods in an enlisted Marine’s career:
- during recruit training,
- before the completion of 24 months of service, given that the Marine successfully completes recruit training, and
- before 45 months of service, given that the Marine successfully completes 24 months of service.
From Table 1, we see that, although the average attrition rate for men during recruit training is 7.6 percent, the predicted recruit training attrition rate for men who score in the top third of all male recruits on the IST is only 5.0 percent. This rate rises to 7.1 percent for men who score in the middle third of the IST, and to 10.2 percent for men who score in the bottom third of the IST. For women, the relationships are similar: higher scores on the DEP IST predict lower attrition rates during recruit training for women.
The 24- and 45-month conditional attrition rates show whether the effect of the IST score on attrition is persistent throughout the course of a Marine’s initial enlistment or whether that effect declines over time. For both men and women, higher IST scores are associated with decreased attrition over the course of a Marine’s first enlistment, but the relative effect of these higher IST scores on attrition rates generally declines throughout the first enlistment. v
DEP IST score and injury rates
We were unable to obtain injury data, so we proxy recruit training injuries as follows: injured recruits are defined as those who were discharged for medical reasons or those who were medically recycled during recruit training.1 To compare men and women, we analyze only recruits trained at Parris Island, since women are only trained at Parris Island.
We find that injury rates during recruit training are lower for both men and women who have higher DEP IST scores. Although the average injury rate for men in recruit training is 3.6 percent, men in the top third of the IST score have only a 2.5 percent predicted injury rate, men in the middle third have a 3.7 percent predicted injury rate, and men in the bottom third have a 4.7 percent predicted injury rate in recruit training. The average female injury rate is 6.0 percent, and the corresponding percentages follow a similar pattern: 4.7, 5.9, and 7.7. Thus, we conclude that higher DEP IST scores predict lower injury rates in recruit training for both men and women.
DEP IST score and PFT and CFT scores
To measure the relationship between the DEP IST score and various PFT scores taken during a Marine’s first enlistment, we classify men and women separately into one of the following categories:
- IST 300 (perfect score),
- IST top third (but not 300),
- IST middle third, and
- IST bottom third.
From Table 2, we see that although the average score for the PFT taken at the end of recruit training for men is 244, the predicted PFT score for men scoring 300 on the DEP IST is 291, the predicted PFT score for men scoring in the top third (but not 300) is 264, the predicted PFT score for men scoring in the middle third is 244, and the predicted PFT score for men scoring in the bottom third is only 224.
For women, the relationships are similar to those for men. Although the average score for the PFT taken at the end of recruit training for women is 250, the predicted PFT score for women scoring 300 on the DEP IST is 291, the predicted PFT score for women scoring in the top third (but not 300) is 267, the predicted PFT score for women scoring in the middle third is 251, and the predicted PFT score for women scoring in the bottom third is only 232.
We conclude, on average, that, for both women and men, recruits who have high scores on the DEP IST are predicted to have high scores on the PFT taken at the end of recruit training as well.
Although the DEP IST is a good predictor of PFT scores in the first two years of a Marine’s initial enlistment, a significant number of men and women go from a low DEP IST to a high PFT, and from a high DEP IST to a low PFT. For example, we find that:
- 13.1 percent of the women who score in the bottom third of the DEP IST later score in the top third (but not 300) PFT at the end of recruit training.
- 13.5 percent of the women who score in the top third (but not 300) of the DEP IST later score in the bottom third of the PFT at the end of recruit training.
The findings for men were similar. These changes are due to both relative and absolute changes in Marines’ measured fitness levels.
This suggests that MOS classification may need to be adjusted once final fitness scores are available at the end of recruit training. Otherwise, some men and women whose physical fitness level is lower than the DEP IST indicated may not succeed in physically demanding MOSs—and some who would succeed in those MOSs will miss opportunities because their DEP IST scores do not indicate their in-service physical fitness level.
We also examined the relationship between the DEP IST score and scores for various CFTs taken during a Marine’s first enlistment, and found similar results.Download full report
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Specific authority: N00014-11-D-0323.
- Pages: 76
- Document Number: DRM-2014-U-007869-FINAL
- Publication Date: 9/24/2014