Dutch Marine recruits: Unexpectedly, cadets with higher levels of grit were not more likely to complete training; it seems grit is not as important as we thought

Grit was not associated to dropout in Dutch Marine recruits. Iris Dijksma, Cees Lucas & Martijn Stuiver. Military Psychology, Mar 2 2022. https://doi.org/10.1080/08995605.2022.2028518

Abstract: Approximately half of all recruits drop out of Marine recruit training. Identifying associated and predisposing factors for dropout would be helpful to understand dropout patterns and induce preventive strategies. Grit has been suggested to be a predictor of who is likely to succeed and who is not. We aimed to investigate the association between baseline grit scores and dropout of Marine recruit training in the Netherlands Armed Forces. We performed an exploratory study using data of three platoons Marine recruit training of the Royal Netherlands Marine Corps. Individual grit levels were measured using the NL-Grit scale, including two subscales. The primary outcome of this study was successful completion or dropout of Marine recruit training. Data were available from 270 recruits, of whom 119 (44%) dropped out of training. The odds ratio for dropout were 1.01 (95% CI 0.84–1.21, p = .917) and 1.07 (95% CI 0.89–1.29, p = .481) per standard deviation increase of consistency of interests and perseverance of effort, respectively. Our study did not confirm the proposed association between baseline grit levels and dropout of Marine recruit training in Dutch Marine recruits using the NL-Grit scale.

Keywords: Gritmilitary trainingretentiondropout

Discussion

Our study aimed to explore the association between baseline grit scores and dropout of Marine recruit training. The results of this study did not confirm the proposed association between baseline grit levels and dropout of Marine recruit training in Dutch Marine recruits using the NL-Grit scale. This finding holds both in recruits who were discharged upon individual request and those who dropout due to musculoskeletal injuries. Explained variance in dropout by baseline grit levels was somewhat higher in the former subgroup than in the latter but lower in both.

Our results do not align with the initial findings by Duckworth and colleagues, who found that grit scores were related to successful completion of military courses (Duckworth et al., 2019; Eskreis-Winkler et al., 2014). Several phenomena may explain why our findings do not suggest an association between grit levels and dropout. First, presumably due to rigorous pre-selection procedures, the data of baseline grit levels per subscale showed a limited range, and they lacked variance (i.e., information). Because of the lack of normative data, we were unable to directly compare subscale sum scores and ranges of our sample to previously study military populations; however, we do assume that cadets at the U.S. Military Academy at West Point would show similarly limited ranges (Crede et al., 2017; Duckworth et al., 2019). The lack of variance is apparent in both subscales, but even more so in the perseverance of effort subscale, which has previously been suggested to be strongly associated with (or even predictive for) performance than consistency of interests (Crede et al., 2017). As a consequence, the possibility to differentiate (i.e., discriminate) recruits based on their grit score is limited. On the other hand, it is possible that within this restricted range, there truly is no association between baseline grit levels and dropout. After all, it is easily conceivable that, as a result of pre-selection, recruits who are fit and brave enough to arrive at the pre-attendance all must possess – and must have addressed – a relatively high level of grit. Possibly, at that point, their grit level contributes less to performance than other traits such as hardiness and resilience (Maddi et al., 2017, 2012). Second, we cannot exclude the possibility of social desirability bias in answering the NL-Grit scale (Grimm, 2010) and the possibility that (young) Marine recruits entertain a less than realistic view of their own grit levels (i.e., measurement bias because of reporting inflated grit levels) (Credé, 2018; Krumpal, 2013).

Although grit as a predictor of military success holds much intuitive appeal, the relation remains uncertain. The measurement of grit levels, and thus the possibility to differentiate, may be improved by adding items to the scale in the higher end of the spectrum. Also, the survey may be taken at an earlier stage in the selection procedure. It is likely that, at that point, the range of grit levels is wider, and the influence of social desirability bias may be less strong.

Limitations and implications

Several limitations of this explorative study are worth highlighting. First, other unmeasured variables may have obscured the association between baseline grit levels and the chance of dropout. Given the explorative nature of this study and the fact that causal paths are far from certain – for example, baseline physical fitness could be considered either a confounder or mediator (Pearl, 2010) – we chose to refrain from controlling for other variables. However, we should also note that the objective of exploring the association of grit with dropout risk was to assess its possible value as a predictor. In prediction research, the causal path and hence considerations about confounding and mediation are irrelevant as long as a variable is a consistent predictor of the outcome. Second, as per common, we measured grit through a self-reported measurement scale. Although it is stated that the act of answering survey questions can increase awareness, which opens the door to development, it also has disadvantages when such self-reported measures are used to detect and quantify associations or even predictive abilities between baseline levels and success outcomes (Oh et al., 2010). Perhaps, observer ratings of personality constructs such as grit levels – or even conscientiousness as an overarching construct – next to self-report methods may yield more valid estimates than the self-report method alone (Oh et al., 2010). Third, the NL-Grit was queried as the last survey, following other surveys. We cannot exclude the possibility that recruits rushed the last survey in order to finish it off. Finally, we wish to emphasize that our study findings are not necessarily generalizable to female military service members (since all participants were male) or other recruit training programs. Future research on both self-reported methods and observer-rated methods, also in other military courses, would add to the understanding of the relation between personality traits and dropout of military training.