The Mississippi Scale for Civilian PTSD (CMS).
- Devised By: The Mississippi Scale for Civilian PTSD is a sub device
of the Mississippi Scale for combat-related PTSD. The Mississippi Scale for
combat-related PTSD was devised by Keane, T.M, Caddell, J.M, and Taylor, K.L.
(1988). This reference is also used when referring to the CMS.
- Type of Instrument: The scale consists of 39 self-report items
derived from the Diagnostic and Statistical Manual of Mental Disorders III-R
criteria for PTSD. The first version of the Mississippi Scale contained 35
items, based on the unrevised DSM-III criteria for PTSD. The four added
items (items 36 to 39) assess re-experiencing, psychogenic amnesia,
hypervigilance, and increased arousal symptomatology (Lauterbach et al,
- Split-half / Cronbach's Alpha: Lauterbach et al (1997) found a
coefficient alpha for the total questionnaire of .89, which is high.
When investigating the alpha for the first and the second half of the
questionnaire these authors found .79 and .81 respectively, thus
deriving a split-half reliability r = .80. These correlations are high
and suggest that the scale measures a single construct (PTSD) and that
the scale is internally consistent.
In other words, the scale can distinguish between persons who have
and those who have not experienced some form of trauma, and between
persons who have experienced different types of trauma.
The original military and the civilian version of the Mississippi
Scale are very similar, and contain parallel items. In the civilian
version the wordings of eleven items have been changed from a military
setting to a more general setting.
Whilst high, the civilian version was found to be less internally
consistent (a ~.89) than the military version
(a ~.94). This could be more a reflection of
the homogeneity of the military population.
- Test-Retest Reliability: Keane et al (1988) calculated the
test-retest reliability of the 35-item military version of the
Mississippi scale with a 1-week interval and found a correlation of .97
(p <.0001). This finding supports the stability of the scale
over brief periods.
- Alternate Form Reliability: NA
- Inter-rater Reliability: NA
- Criterion Validity: In the Lauterbach et al
(1997) studies higher scores on the civilian scale were related to
having experienced a traumatic event. In both studies the group who had
experienced some sort of trauma scored significantly higher on the
measure (Study I: F(1,433) = 12.9, p <.0005; Study II: F(1,398)
= 8.93, p <.003).
- Content Validity: The CMS measures a single construct
(presumably PTSD). However, there is much discusion and confusion
regarding the degree to which the Mississippi measures just PTSD or PTSD
- Discriminant Validity: In addition, they found correlations of
.71 with the Beck Depression Inventory (BDI) and of .70 with the Trait
version of the State-Trait Anxiety Inventory (STAI-T). These
correlations are in the moderate to high range. All these tests were
significant at p <.0001.
These findings with respect to convergent and discriminant validity
indicate that the CMS is more strongly related to measures of depression
and anxiety than to other measures of PTSD, suggesting that the Civilian
Scale measures general psychological distress or negative affect rather
than specific PTSD symptomatology.
- Scoring Method: Each item is rated on a 5-point Likert scale, with
items 2, 6, 11, 17, 19, 22, 24, 27, 30, and 34 scored in the reverse order
(i.e. subtract their rating from 6). All the items are than added to obtain
a total score on the scale.
The norm groups have the following means and standard deviation measures:
PTSD patients: 130, SD = 18
Psychiatric patients: 86, SD = 26
Normal controls: 76, SD = 18
However, these are norms for the combat-related version of the
Mississippi scale, since at this stage there are no norms available for the
civilian version. In the Lauterbach et al (1997) study, subjects were
psychology students, who scored a mean of 82.9 (SD = 16.3).
Devilly, G.J. and Spence, S.H. (1999). The relative efficacy and
treatment distress of EMDR and a cognitive-behavior trauma treatment
protocol in the amelioration of posttraumatic stress disorder. Journal of
Anxiety Disorders, 13, 131-157.
Keane, T.M., Caddell, J.M., and Taylor, K.L. (1988). Mississippi scale
for combat-related posttraumatic stress disorder: Three studies in
reliability and validity. Journal of Consulting and Clinical Psychology,
Lauterbach, D., Vrana, S., King, D.W., and King, L.A. (1997).
Psychometric properties of the Civilian version of the Mississippi PTSC
scale. Journal of Traumatic Stress, 10, 499-513.
See here for questionnaire availability
Above written by: Ms. Marjan Geertsema
Reviewed, edited and approved by: Dr. Grant J. Devilly