Cover Letter for manuscript ID 8067696411622604- A FACTOR ANALYTIC
INVESTIGATION OF THE TRIPARTITE MODEL OF AFFECT IN A CLINICAL
SAMPLE OF YOUNG AUSTRALIANS
Dear editor
We thank the reviewers for their prompt assessment of our manuscript and for
the useful comments to improve this paper. We have edited the manuscript as
per the reviewers’ comments and have addressed each of their concerns (see
below). I hope this revision is acceptable, and we look forward to hearing the
outcome of our corrections.
Kind regards,
Joe Buckby.
Reviewer's 1 report
Reviewer: Carl F Weems
Reviewer's report:
1. An initial main concern is that the paper’s main aim is not clear from the introduction and this makes an
evaluation of the significance and incremental contribution of the study difficult to determine. In particular,
it is not clear whether this is a psychometric investigation of the MASQ’s factor structure or a theoretical
test of the tripartite model. To some extent my guess is that the authors wish to do both but the present
version does not accomplish the set up for this and depending on the main goal I would expect to see very
different statistical tests. For example, the title states that this is a factor analytic investigation of the
tripartite model but the abstract implies a test of the MASQ. If the goal is to test the tripartite model in a
new sample then I would expect confirmatory factor analysis (CFA) for the factor analysis coupled with
some person centered analyses (e.g., a comparison of anxiety disordered versus depressive disorder patients
versus non disordered). We (Cannon and Weems, 2006) recently did a paper that tested the tripartite model
using person centered (analyses cluster analysis) and that paper may be a useful reference. If the goal was
testing the factor structure then I think there is more than adequate data for a-priori test of item loadings
CFA) versus EFA. In other words I think the field has moved beyond the question of exploring the
structure of affect. An EFA might be reasonable in an initial psychometric evaluation of the MASQ-but it is
not clear that this is the goal of the paper.
REPLY: We have attempted to clarify the introduction in order to make the
aims and rationale for this paper more clear. We then re-analysed the data as
suggested above. We conducted confirmatory factor analysis (CFA) to determine
the most appropriate model for the data in our sample of help-seeking
adolescents and young adults. We aimed to determine whether the predicted
structure of PA, NA and PH would emerge when subjecting the MASQ to a series
of CFA. In devising the competing models, we were guided by previous findings
to create a number of competing 3-factor and 2-factor solutions. Though a 3factor model was found to be acceptable, a 2-factor model (depression and
anxiety) was found to demonstrate a significantly better fit. This unexpected
finding is discussed.
2. Page 3, the authors contrast the tripartite model with what they refer to as a continuum model.
However the presentation is unclear how would anxiety and depression form a continuum? Do
they mean single construct?
REPLY: You are correct, we do mean that anxiety and depression would form
opposing poles of a single construct. We have expanded this point in paragraph
1, page 3.
3. Page 3, the link between the labels of the components of the tripartite model and
the descriptors of the components is a bit unclear.
REPLY: Thank you for noticing this. We have restructured this paragraph
(paragraph 2, page 3) in order to make our description of the tripartite model
more clear.
4. Page 4, I have to disagree with the statement that “the majority of research into the validity of
the tripartite model has been conducted using measures that were not designed to measure the
tripartite constructs. At best it is misleading and worst wrong. One need simply do a lit search of
the positive and negative affect scale (PANAS) or the original paper on the topic by Watson and
Clark to see that the measure has been cited over 600 times.
REPLY: To the best of our knowledge the MASQ is the only self-report measure
that was specifically designed to test all three components of the Tripartite model
of affect. A small number of studies have looked at the psychometric properties
of this instrument, but there is very little data from clinical samples that have
investigated the Tripartite model with the MASQ. While it is true that there is a
very large body of research that has utilised the PANAS, it is only a minority of
these studies that have explicitly used it to test the Tripartite model. The majority
of the studies that we have reviewed have used measures of anxiety (e.g.
RCMAS, BAI) as a proxy for the anxiety component of the tripartite model. While
the items that are chosen from the scales match those from the MASQ
reasonably well, they were not specifically designed for this purpose. Other
studies that have investigated the Tripartite model using the PANAS have not
included any measure of the core component of anxiety and have instead
provided evidence for the distinction between NA and PA and have inferred the
distinctiveness of all three constructs from this. However, we have modified this
particular paragraph (inserted the word ‘specifically’) in order to make the point
more clearly.
Page 5, the authors suggest it is important to test in “older adolescents” How so exactly? If the
theory is valid in adults and younger children why would we expect it to not be in peoples of ages
between those? I am not saying there is not a reason just that the authors need to give a good
reason.
REPLY: Late adolescence and early adulthood is the time of peak onset of
psychiatric disorders. Young people’s disorders during this period may not have
clearly differentiated into clearly diagnosable disorders and may instead present
with high levels of mixed symptomatology that can not clearly be categorised into
DSM diagnoses (or Tripartite dimensions). Therefore, it is important to test the
Tripartite model in this group in order to better understand these constructs and
in order to better inform treatment for these young people. The relevant
paragraph has been modified to better reflect this argument. Thank you for
bringing it to our attention.
Page 5 and on, The authors expect a factor structure consistent with the tripartite model, three
factors but the MASQ appears to have five scales (see Table 1)? Why would the authors not
expect 5 factors? I thought --well maybe they did not use items from two scales but I could not
find that information clearly presented. The methodology and expectations for the number factors
is thus made very confusing by the unclear theoretical set up of the introduction.
REPLY: The exploratory factor analysis section has been replaced with new
analyses (see above).
Page 6, how was informed consent obtained from underage participants, were
they all of age? If so what is the legal age of consent in Australia?
REPLY: The legal age of consent in Australia is 18. For younger participants,
consent was sought from parents/legal guardians and assent was gained from
the young people. This statement has been added to this paragraph.
Page 7, I really think in terms of data entry there should be 0% incorrectly entered data in the
data set. Really we should be reasonably certain that the data was all entered correctly. Were
incorrect data, corrected?
REPLY: We were advised by our statistician that because a very small proportion
of re-entered data were incorrect, it would not be necessary to re-enter the entire
data set in order to run a complete data verification. The criteria for this decision
was set at 0.5% (i.e. only a single data entry mistake was allowable per 200 data
points). The few data entry mistakes that were identified were corrected prior to
analysis. This statement has been added to this paragraph.
Page 7, the authors note that oblique rotation was used but that previous research used
orthogonal rotation was used previously with the MASQ—I wondered why not compare solutions.
However, I also wondered why not CFA (see above)?
REPLY: As described above, EFA was replaced with CFA to directly compare
solutions.
Page 8, what was the age range of the final sample?
REPLY: The final age range was 15-24 (same as for the sample as a whole).
This has been inserted into the manuscript.
Page 8, I wondered about comorbidity and the possibility of comparing anxiety disordered versus
depressive disorder patients versus non disordered patients, on subscales of the MASQ or
possibly cluster MASQ defined groups. Such an analysis would strengthen the paper.
REPLY: This is a very important point. We have previously published this data
that compared the various diagnostic categories (‘pure’ depression & anxiety,
comorbid depression-anxiety, no depression-anxiety). We have referenced this
paper in the present manuscript in both the introduction and discussion in order
to strengthen the argument that factor analysis of the tripartite model is required
in this unique sample.
Page 9, I did not this the parallel analysis information should be footnoted, this appears to be a
major test of the authors factor structure and is a somewhat uncommon method that should be
well described. However, CFA would eliminate the need.
REPLY: As noted above, EFA has been removed from this paper and this point
is no longer an issue.
I felt Tables 2 and 3 could probably be combined.
REPLY: They have both been removed and replaced with results from the CFA.
Reviewer's 2 report
Reviewer: Edwin de Beurs
Reviewer's report:
General
------------------------------------------------------------------------------Major Compulsory Revisions (that the author must respond to before a decision
on publication can be reached)
The authors seem to have overlooked the fact that the second factor of the 3-factor model is
predominantly composed of positive affect items (that need reverse scoring to measure lack of
positive affect). The anhedonia items which describe negative feelings group with the Negative
Affect items. Moreover, the second factor of the 2 factor model consist entirely of positive affect
items. This is very likely a method effect, stemming from artifacts of measurement (e.g., the
tendency of respondents to choose the low or high end of the response scale). Unfortunately,
EFA can produce misleading results when a method effect exists in the data (see Brown, 2006,
Confirmatory Factor Analysis for Applied Research). This contention is relevant to the heart of the
tripartite model (or at least to the suitability of the MASQ to assess the three dimensions of the
model) as it challenges the distinctness of negative affect and lack of positive affect.
With EFA this can not be resolved. CFA is better suited for these data as a single trait factor can
be specified (for PA and NA) and a method effect (correlated errors) for the items with positively
worded affects. As there is a clear model for the 3 factorial structure of the MASQ (see also
Keogh and Reidy, 2000 or de Beurs et al., BR&T, 2007), there is no reason to fall back on EFA
and CFA is the preferred method of analysis for the factor structure. The authors mention in the
abstract that measures were taken to ensure factorability of the data in spite of the insufficient N
for factor analysis. In the results section they present favourable results regarding the factorability
of the data. The ratio of items to subjects is nevertheless far from the required 1 : 5 that
is generally recommended to acquire a replicable factor solution. This is an additional reason to
refrain from exploratory factor analysis and choose confirmatory factor analysis instead.
REPLY: These suggestions were almost identical to those of reviewer 1. And we
have therefore re-analysed the data with CFA rather than EFA. Though our
results were somewhat different to those that we originally reported (i.e. a 2-
factor rather than 3-factor solution proved to best fit the data), we believe these
findings are defensible and not so divergent from those reported elsewhere in the
literature. We have discussed these findings in detail in the discussion and
conclusion sections. Our present results indicated that both sets of depression
items (loss of interest and high positive affect) related to the same construct and
that the model was strengthened by having them grouped together. These
findings support your assertion that a likely method effect underlies the apparent
distinctiveness that has been reported in EFA. This point has been made in the
discussion section.
------------------------------------------------------------------------------Minor Essential Revisions (such as missing labels on figures, or the wrong use of
a term, which the author can be trusted to correct)
Minor points:
Is the GAS scale the same as the GAF scale of the DSM-IV (Global Assessment of Functioning)?
If so the proper reference is missing, if not the reference for the adult version is missing. In fact,
the scale is not used in the analyses, so it could be omitted from the methods section all together.
REPLY: We have removed reference to the GAS and the small section that
referenced this measure.
The authors write that: “Thirteen cases with more than 25% of questionnaire data missing were
deleted from subsequent analyses, leaving 137 participants with complete data.” “leaving 137
participant who completed at least 75% of the items” would be a more appropriate phrase.
REPLY: This section has been amended as per your suggestion.