Identify research studies and define hypotheses.

Identify three to five quantitative research studies from peer-reviewed sources, which
were published within the last ten years that investigate this topic. Describe the
statistical approaches (e.g., identify each variable and its type) used in each study and
the interpretation of the results. Finally, present other statistical approaches that could
have been used and, when appropriate, suggest alternative interpretations of the results.
The three to five quantitative research studies that have been conducted on your chosen
topic must:

Have a clearly stated research hypothesis.
Utilize inferential statistical tests as part of the research study.
Present the results of the statistical analysis.
Interpret the results of the statistical analysis.
Discuss the implications of the results of the study.
The Final Paper must contain the following sections:

Introduction: Identify research studies and define hypotheses.
This section will provide a general introduction and review relevant literature to the
topic being studied. Identify three to five quantitative research studies from peer-
reviewed sources, which were published within the last ten years that investigate this
topic and meet the five stated criteria (listed above). The research hypothesis associated
with each study should also be clearly defined.
Methods: Describe the statistical approaches.
In this section, the research method and statistical approaches for each of the studies
being critiqued will be presented. This section should include a description of all
statistical tests conducted and other relevant information, such as the sample size, and
any assumptions noted on the part of the researcher. In this section, the student should
describe of all of these factors, and suggest alternatives when they are appropriate.
Results: Critique the results.
In this section, the results of the statistical tests performed in each of these studies
should be presented and critiqued. It is appropriate in this section, to discuss limitations
or to critique the interpretation of the results provided in each study.
Discussion: Compare efficacy.


This section will compare the efficacy of the research studies that are presented on the
topic chosen by the student. The strengths and weaknesses of each study should be
mentioned in this section. Based on these studies, suggest future research directions.
Additional forms of statistical analysis should be included as part of the suggested
future research.

Effect of Post-Traumatic Stress Disorder among Veterans and Active Duty


Post-traumatic stress disorder (PTSD) is a condition that is caused by either
witnessing or being directly affected by a traumatic event. There are many events that can
lead to PTSD but now, there is one popular source of the condition; war on terrorism. When
talking about the war on terrorism, the deployment of US military forces in countries such as
Iraq and Afghanistan comes to mind. This is especially so among those who have already left
the military, better known as veterans. According to Vaterling et al, cases of PTSD among
US Iraq war veterans are very high at about 12% for recently returned soldiers (Vasterling,
For the last ten years, some studies have been done on the effects of the war on the
mental health of soldiers with focus on PTSD. Recognizing such works is important as it
serves to show how this problem is highly regarded or lack of it. This paper reviews four
scholarly papers that have been prepared by different researchers in the last ten years and
lightly analyses various statistical approaches such as variables, sample size, and the results,
and so on. The four research papers featured here are:

  1. “The Psychological Costs of War: Military Combat and Mental Health”,


  1. The Effects Of GWOT And Deployment Intensity On The Propensity To
    Develop Post-Traumatic Stress Disorder (PTSD) Among Navy Personnel
  2. “Delayed-Onset Post-Traumatic Stress Disorder Among War Veterans In
    Primary Care Clinics”, and
  3. “PTSD Symptom Increases in Iraqi-Deployed Soldiers: Comparison with
    Non-Deployed Soldiers and Associations with Baseline Symptoms, Deployment Experiences,
    and Post-Deployment Stress”.
    All the four studies were done after 2008 so they are less than 5 years old. As it will
    be clear in the methods part of this paper, the featured papers have hypothesis, use inferential
    statistics tests, and present, interpret and discuss the results.
    In the research “The Psychological Costs Of War: Military Combat And Mental Health”,
    Cesur Resul and co-authors show how soldiers involved in the global war on terrorism suffer
    from the risk of PTSD and suicidal ideation, and the researchers proceeded to estimate the
    cost of combat induced PTSD (Cesur et al, ). As indicated, Cesur’s paper sought to give a
    monetary attachment to the Global War on Terrorism (GWOT) recognizing that most
    previous studies have only concentrated on descriptions (Cesur, Sabia & Tekin, April 2011).
    The hypothesis for this study was that “combat service is associated with mental health
    problems and that the mechanism is driven by potentially psycho-traumatic incidences
    experienced during combat zone missions” (Cesur, Sabia & Tekin, April 2011).
    “The Effects of GWOT and Deployment Intensity on the Propensity to Develop Post-
    Traumatic Stress Disorder (PTSD) Among Navy Personnel” is yet another research that
    sought to illuminate on the link between deployment intensity and effects of GWOT on
    PTSD among the navy. The aim of this research was to determine the trend PTSD in sailors
    with the help of medical data sourced from Army Medical Surveillance Activity (AMSA) and


Defense Manpower Data Centre (DMDC). This research marked the first time the US
military was supporting research on PTSD through medical health advisory team reports
(citation). In the clinical definition of PTSD, the Diagnostic and Statistical Manual of Mental
Disorders (DSM), which is published by the American Psychiatric Association is used
(citation). Some of the criteria highlighted in this paper include:
 Longer-than-a-month symptoms

 Hyper awareness
 Hampered ability to continue with normal daily activities
 Serious injury or death experiences as a witness

 Avoidance of similar or experiences that remind of traumatic event
 Reliving the times disturbing times for example flashbacks, distressing
memories, nightmares and physical reactions
 Horrific or intensely fearful reaction to a situation

This paper hypothesized that “as the number and frequency of deployments increase,
the propensity to develop PTSD is positively affected” (Cesur, Sabia & Tekin, April 2011).
The paper “Delayed-Onset Post-Traumatic Stress Disorder among War Veterans in
Primary Care Clinics” came against the understanding that there is limited empirical data in
the area of delayed-onset PTSD. Fruel et al started by noting that delayed-onset PTSD is
common both in the military and among civilians. Identifying critics to delayed-onset PTSD,
the authors identified several studies that have touched on this topic in the recent past, and


these include large-scale and small-scale research. The hypothesis of this paper was that
delayed onset PTSD is rare in veterans 1 year into the post-trauma period (Fruel, 2009).
“PTSD Symptom Increases in Iraqi-Deployed Soldiers: Comparison with Non-
Deployed Soldiers and Associations with Baseline Symptoms, Deployment Experiences, and
Post-Deployment Stress” is a prospective study that sought to examine the effects of
deployment in Iraq on soldiers as compared to non-deployment. The study further highlighted
on the deployed soldiers PTSD symptoms changes with the level of exposure. For this study,
the main hypothesis was that PTSD symptoms levels were directly proportional to Iraqi
deployment (Vasterling, 2010).

Cesur’s paper sourced data from the National Longitudinal Study of Adolescent
Health (Add Health). Add Health has been surveying adolescents from 7 th to 12 th grade since
the 1990s. The first baseline survey was conducted in the 1993-1994 US academic year and
involved 20,745 respondents. The follow-up survey came a year later in 1996, with wave III
of the baseline survey being conducted in 2001. There was also a third follow-up or wave IV
that targeted 15,701 members of the first baseline survey in 2007-2008 (Cesur, Sabia &
Tekin, April 2011).
As Cesur notes, this data is relevant as it tells whether a service member was in the
warzone or worked in a noncombat zone. Secondly, the data collected by Add Health
advanced the research because it covered a wide range of military service members. The
hypothesis to Cesur’s study is that combat service is associated with mental health problems.


Apart from the large sample of military members (N=1,110), this data contained information
on active-duty service personnel deployed to combat zone (N=439), active duty in the US
alone (N=343,), and non-combat zone outside the country (N=153). With so much data from
Add health, this research restricted itself to Wave IV respondents who were at the ages of 24-
33 years (Cesur, Sabia & Tekin, April 2011).
The dataset from Add Health was quite huge and the study created two master
datasets. This was important as it enabled the Pilgrim and fellow researchers to deal with
easier personal information. Therefore, out of an original number of 13,433 officer
observations and 119,126 enlisted observations, Pilgrim and company remained with a
comfortable 13,096 and 114,023 observations respectively (Pilgrim, 2008).
In collecting data from the active duty personnel file, care had to be taken to ensure
that only information on GWOT about the navy was collected. Therefore, all data before
2002 was deleted and that for other forces other than the navy as well. As a way of getting the
different types of deployments, this research went to Active Duty Pay File and additional
payments that were relevant indicators of deployment. The independent variables for this
study included sex, rank, deployment history, marital status, and education level (Pilgrim,
For post-deployment assessment, the research relied on responses on the DD2796
form, specifically question no. 12 that reads; “Have you ever had any experience that was so
frightening, horrible, or upsetting that in the past month, you…” In this case, the independent
variable is the propensity to develop PTSD and was gauged on how the serviceperson
responded to the question from the categories that were provided (Pilgrim, 2008).


Participants in the study “PTSD Symptom Increases In Iraqi-Deployed Soldiers:
Comparison With Non-Deployed Soldiers and Associations with Baseline Symptoms,
Deployment Experiences, and Post-Deployment Stress” were female and male US Army
soldiers and activated National Guard Soldiers who served between 2003 and 2006
(Vasterling et al). In this study, pre-deployment and post-deployment assessment was done
for deployers. While the military battalion level formed the location for sampling,
heterogeneous deployment experiences is one aspect that had to be considered. To take care
of this, the study selected participants from combat support, combat arms, and service support
functions (Vasterling, 2010). To get a sample population from these groups, unit leaders
picked every third name on the unit roster for participants this being a random selection.
This study invited about 1633 soldiers and 94% of those agreed to participate. Of
these, 24% had separated from the service, 48% had relocated, while 5% had
unknown/unrevealed reasons. After the questionnaire exercise, 41 soldiers were excluded
leaving 1083 soldiers for the final sample. In these, 774 were deployed soldiers while 309
soldiers were non-deploying (Vasterling, 2010).
To get the independent variables on military and demographic information, surveys,
and interviews were used while stress exposures were assessed through written
questionnaires. The written surveys were done at military installations through a larger study
that targeted neuro-cognitive functioning (Vasterling, 2010).
Results: Critique the Results
It is important to compare the results of the four studies highlighted in this paper. In
Cesur’s paper, the research results were presented using a Ordinary Least Square (OLS)


model of the form yi = α + δ1Activei + δ2Non-Active Dutyi+ Xi β + εi with indicators for
mental health outcomes, active duty military service, background & individual characteristics
(Cesur, Sabia & Tekin, April 2011). Consequently, the estimates for δ1 and δ2 were
presented in a table.
In Pilgrim’s research, the results were for five models, although all of them featured
same service and demographic information. Only the variable type was altered in each case.
In model 1, the resulting coefficients of .05 levels were positive suggesting that soldiers
deployed after the start of the GWOT had a higher propensity to develop PTSD than those
deployed earlier did. For hostile deployment, the coefficient estimate stood at .01 levels.
Soldiers deployed in a hostile region had a 4.1 percent higher risk of getting PTSD than those
on non-hostile zones (Pilgrim, 2008).
The results also looked into the deployment duration and the coefficient estimates
were insignificant in this case (Pilgrim, 2008). This meant that the duration of deployment
had no bearing on the propensity to develop PTSD, at least for an average soldier.
Going to model 3, the focus was on duration lengths for hostile deployment. Here
also, the coefficient estimates were statistically insignificant meaning that for the average
navy officer, the propensity to acquire PTSD remains unchanged with time even in hostile
deployment zones (Pilgrim, 2008).
Model 4 in Pilgrim’s study focused on the comparison between soldiers who were
deployed in hostile zones in the previous 36 months and those who were not deployed in such
zones (Pilgrim, 2008).


In Fruel et al paper, 8.3 %( current PTSD) of the sample of 84 veterans satisfied the
conditions for delayed-onset PTSD. For sub-threshold PTSD and lifetime PTSD only, 6.9%
and 5.4% respectively met the requirements for delayed PTSD. Owing to the low number of
veterans with delayed-onset PTSD for the three cases, the researchers saw no need for
secondary analyses for correlates and predictors. However, some important observations from
the current PTSD in this research: Six soldiers had multiple traumatic experiences, six were
men, and only one soldier was over 65 years of age (Fruel, 2009).
Vasterling et al conclude that the adjusted change score for deployed soldiers was
3.65 points higher than that for non-deployed colleagues. When the researchers did follow up
tests, there mean PCL scores increased significantly from pre-deployment to post-deployment
among the deployed group of soldiers. In the non-deployed group, PCL scores for pre-
deployment and post-deployment showed insignificant difference (Vasterling, 2010).
Discussion: Compare Efficacy
Cesur’s paper is a suitable gauge of how the wars in Afghanistan and Iraq, where the
US has deployed over 2 million soldiers in the last decade, have had a causal effect on young
soldiers. The research has considered unmeasured heterogeneity and exogenous variation.
The results from this study support the hypothesis that the psycho-traumatic experiences of
combat zones contribute to mental health problems for army combatants. Using estimates for
PTSD costs per soldier, the research manages to estimate a total healthcare cost of $2.69
billion for this PTSD (Cesur, Sabia & Tekin, April 2011).
Pilgrim’s research took a slightly different research route, but the results concur with
the Cesur’s findings. Firstly, this paper discovered several factors that affected the propensity


to acquire PTSD among sailors and officers (Pilgrim, 2008). Examples of these factors
include marital status and age. Interestingly, the higher rank naval officers showed higher
propensity to develop the condition.
Centre to this research was the fact that the impact on PTSD rates was similar in both
sailors and officers if they were deployed to a hostile zone (Pilgrim, 2008). Further, the
duration of deployment did not have significant effect on the propensity to develop PTSD
unless such an officer had served in a hostile region at least once in the previous 36 months.
The results were different for sailors although this may be attributed to the fact that the
average age of a sailor is lower.
For Fruel et al, study results indicated that although PTSD occurs, delayed onset
PTSD is not as common among veterans (Fruel, 2009). This is against a general expectation
of high instances of PTSD considering that delayed onset takes sometime to appear. Reports
in this research indicate older veterans undergoing PTSD treatment record lower rates of the
condition than a younger age group of veterans taking the same treatment.
Vesterling et al research showed that deployment in the Iraqi war zone contributed in
an increase in PTSD symptoms in both the pre-deployment and post-deployment periods.
Although this research did not fully take into account the correlation the PTSD outcome with
the duration after leaving Iraq, there is a possibility that the timeframe could have affected the
National Guard and regular active duty.



Cesur, R., Sabia, J. J., & Tekin, E. The Institute for the Study of Labor (IZA), (April
2011). The psychological costs of war: Military combat and mental health. Retrieved
from University of Bonn website:
Fruel , B. C. (2009). Delayed-onset post-traumatic stress disorder among war veterans in
primary care clinics. The British Journal of Psychiatry, (194), 515-520.
Pilgrim, J. L. (2008). The effects of GWOT and deployment intensity on the propensity to
develop post-traumatic stress disorder (PTSD) among navy personnel. (Master’s


Vasterling, J. J. (2010). PTSD symptom increases 1ll Iraq-deployed soldiers: Comparison
with nondeployed soldiers and associations with baseline symptoms, deployment
experiences, and post deployment stress. Journal of Traumatic Stress, 23(1), 41-51.