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Lauren MaloneDavid GregoryAnn Parcell
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In this annotated briefing, we examine the relationship between dual-enlisted couples’ colocation and reenlistment in the Navy. This analysis is part of a larger CNA project titled “The Effects of Personnel Policy Changes on Budgets and Manpower Inventories” sponsored by the Office of the Assistant Secretary of the Navy (Financial Management and Comptroller) (ASN(FM&C)).

Background for study

In the larger project, we aim to identify and explore ways to reduce personnel costs while maintaining or even improving retention. The impetus for the project is that military personnel costs, including those in the Department of the Navy (DON), are quite large and are always under scrutiny. DON must continuously strive to make the personnel system more effective and efficient.

Additionally, DON has pushed to increase the female share of accessions and inventory. This has implications for retention and manning the fleet. Historically, women in the Navy have not retained as well as men. In addition, pregnancy, and operational deferment, along with higher limited duty rates for females, can make manning the fleet more challenging.

The research agenda for this project revolves around four issues related to the cost of DON uniformed personnel. (These four issues are briefly described in the next slide.) In particular, the sponsor is interested in how costs may change as the female share of the uniformed personnel in DON increases; three of the four issues directly relate to the female share of the active component inventory.

Colocation: 1 of 4 issues addressed in a larger study

These are the four main issues to be addressed in the larger project.

In this annotated briefing, we address issue number three. Colocation in the Navy is when two servicemembers who are married to each other (also known as a dual-military marriage or couple) are assigned to units no further than 90 (driving) miles apart. A dual military couple is not colocated if the units to which they are assigned are greater than 90 miles apart.

Our analysis is motivated by the possibility that, as the share of women in the services increases, there may be an increase in dual-military marriages, as well as an increase in the demand for colocation. Therefore, it is increasingly important to examine the third question above—that is, to know whether the decision of servicemembers in dual-military marriages to reenlist may be affected by colocation. In this annotated briefing, we specifically examine the following aspects of this question:

  • How often are dual-enlisted Navy couples able to be colocated?
  • How does colocation of dual-enlisted Navy couples affect reenlistment decisions?
  • As a result, what are the potential implications for personnel costs?

The remaining three issues in the larger study are addressed in other research documents.


Our approach is to use Navy personnel records to identify sailors who are married to other service personnel, including other sailors. We focus on enlisted Navy-Navy couples because the Navy enlisted force is the largest of the DON active components and has the greatest share of women.

Per Navy policy, an enlisted Navy-Navy couple is defined as being colocated if the two sailors’ assigned locations are within 90 (driving) miles of each other. Our distance measure only allows us to determine whether the Navy-Navy couple is assigned to units that are 90 miles apart (not 90 driving miles). Note that the Navy policy measure, and the measure we use in this analysis, is distance between assignments, not distance from residence to assignments. (We also tested a difference of 50 miles to determine whether there were significantly different effects from being assigned to locations closer than 90 miles, and there were not.)

Using CNA’s decision file, we determined the marital and colocation status of sailors at the time of their reenlistment decisions. We then estimated the relationship between colocation and the probability of reenlistment. We considered the costs and benefits of colocation compared with other reenlistment incentives.

This annotated briefing presents our enlisted Navy-Navy results. Our next report will present the enlisted MC-MC results. Once that analysis is complete, we will consider whether sample sizes and resources allow for analysis of Navy and MC officer colocation as well as analysis of colocation of spouses in which one member is in the Navy and the other is in the MC.

Summary of findings

Our estimates suggest that colocation is associated with a higher probability of reenlisting, and that the impact is especially large for women. For example, at the Zone A reenlistment decision, we estimate that colocated female sailors are 8.6 percentage points (ppts) more likely to reenlist than their noncolocated counterparts (51.3 vice 42.6 percent). The estimated effect for men is smaller but still positive; we estimate about a 5.5-ppt increase in Zone A reenlistment rates for colocated vice noncolocated male sailors (69.7 vice 64.2 percent).

At Zone B, our estimates suggest that colocated women are 11.6 ppts more likely to reenlist than their noncolocated counterparts (62.9 vice 51.3 percent). We find no statistically significant difference in the estimated probability of reenlisting for colocated vice noncolocated men at Zone B (i.e., we find an estimated difference of 74.4 vice 70.4 percent, but the difference is not statistically different from zero).

At Zone C, the difference in the estimated probability of reenlisting for colocated vice noncolocated women is 10.1 ppts (81.8 vice 71.7 percent). For men, the difference is 8.5 ppts (86.6 vice 78.1 percent).

If we assume that most sailors who have civilian (civ) spouses are able to live with their spouses, we can compare the estimated probabilities of reenlisting for colocated sailors vice those with civ spouses to isolate the specific effect of Navy spousal cohabitation. We find that spousal cohabitation with either a Navy or a civ spouse appears to be more important for Zone A female sailors’ reenlistment decisions, whereas cohabitation with a Navy spouse appears to be more important for Zones A and B male sailors’ reenlistment decisions and for Zone B female sailors’ decisions.

Finally, we report an unexpected result: at the Zone A decision point, single female sailors have a higher estimated probability of reenlisting than single male sailors. Single sailors make up the majority of both female and male sailors at the Zone A decision point, so the result reflects the behavior of the majority of first-term decision-eligible sailors.

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DISTRIBUTION STATEMENT A. Approved for public release: distribution unlimited.


  • Pages: 26
  • Document Number: DAB-2018-U-016844-Final
  • Publication Date: 5/18/2018
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