1. Cumulative probability of being in one ordinal response category (or above)

2. IRT Item information functions for GHQ-12 (in a primary care sample) under Samejima’s
graded response model (GRM) : panels are ordered 6 positive items then six negative

3. Coeff Thresh 1 2 3 Discrimination 1 -1.850 0.491 1.894 2.366

4. Scale scores (Emp Bayes)
factor.scores(ghq12ord4)
Factor-Scores for observed response patterns:
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12 Obs Exp z1 se.z1

5. Positively worded items scored 1000
GHQ01
GHQ03
GHQ04
GHQ07
GHQ08
GHQ12 F1
GHQ
Pos F2
GHQ
Neg
Orthogonal
GHQ02
GHQ05
GHQ06
GHQ09
GHQ10
GHQ11
Negatively items scored 0011

6. cut ighq_+ (1) ighq_- (2) IGHQA Category 1 0.058 Category 2 0.942
IGHQC
Category
Category
IGHQD
Category
Category
IGHQG
Category
Category
IGHQH
Category
Category
IGHQL
Category
Category
IGHQB
Category
Category
IGHQE
Category
Category
IGHQF
Category
Category
IGHQI
Category
Category
IGHQJ
Category
Category
IGHQK
Category
Category

7. 1 v 2 factor: 1000+(pos) 0011-(neg)
RMSEA ESTIMATE IS
ROOT MEAN SQUARE RESIDUAL IS
VARIMAX ROTATED LOADINGS
________ ________
IGHQB
IGHQE
IGHQF
IGHQI
IGHQJ
IGHQK
IGHQA
IGHQC
IGHQD
IGHQG
IGHQH
IGHQL
PROMAX ROTATED LOADINGS
IGHQB
IGHQE
IGHQF
IGHQI
IGHQJ
IGHQK
IGHQA
IGHQC
IGHQD
IGHQG
IGHQH
IGHQL
PROMAX FACTOR CORRELATIONS
EXPLORATORY ANALYSIS WITH 1 FACTOR(S) :
RMSEA ESTIMATE IS
ROOT MEAN SQUARE RESIDUAL IS
ESTIMATED FACTOR LOADINGS 1
________
IGHQB
IGHQE
IGHQF
IGHQI
IGHQJ
IGHQK
IGHQA
IGHQC
IGHQD
IGHQG
IGHQH
IGHQL

8. SCREENING FOR ? Positive (mental) health/ Change in health
SCREENING FOR CMD Anxiety
+ Depression

9. so …
What does 1000 scoring of GHQ positive items do/measure? A. Recent change in (physical) health? B. Vitality/Energy? C. A second as yet unknown dimension of psychosocial functioning/positive health? D. Well-being (what’s that?!) And why study this alongside GHQ negative items scored as 0011? …

10. Able to concentrate
Lost much sleep
Playing a useful part
Capable of making decisions
Under stress
Could not overcome difficulties
Enjoy normal activities
Can face up to problems
Feeling unhappy and depressed
Losing confidence
Thinking of self as worthless
Feeling reasonably happy

11. Limitations Future opportunities
Analyses not currently sensitive to household clustering issues
Analyses clearly not making use of valuable, relevant and extensive, longitudinal data (!!!!)
Not all construct validity domains exploited
CASP (next speaker), Life satisfaction
Future opportunities
Big Five personality data collected on BHPS survey members (50 items) in wave 15; data now available?

14. From Data to Paper (via Stata)
That’s all folks:
tell us what you think
IT’S FEEDBACK TIME

16. http://psychometrics. sps. cam. ac. uk/page/184/stata
Written byJean-Benoit Hardouin (University of Nantes)

17. Methods for uni- and multiple dimensions: new models for multi-item measures when uni-dimensional means “somewhat multidimensional”

18. Latent structure models some schematics: GHQ-28B D C

19. General and Specific Factors
General factor – loadded by all items
Specific factors – orthogonal to General, and to eachother (Specifics)

21. “A plausible factorial structure for many types
Full-Information Item Bifactor Analysis of Graded Response Data Bhaumik, David J. Kupfer, Ellen Frank, Victoria J. Grochocinski and Angela Stover Robert D. Gibbons, R. Darrell Bock, Donald Hedeker, David J. Weiss, Eisuke Segawa, Dulal K. Applied Psychological Measurement 2007; 31; 4
“A plausible factorial structure for many types
of psychological and educational tests exhibits
a general factor and one or more group or method
factors. This structure can be represented by
a bifactor model. The bifactor structure results
from the constraint that each item has a nonzero
loading on the primary dimension and, at most,
one of the group factors. The authors develop
estimation procedures for fitting the graded
response model when the data follow the bifactor
structure.

22. Full-Information Item Bifactor Analysis of Graded Response Data Bhaumik, David J. Kupfer, Ellen Frank, Victoria J. Grochocinski and Angela Stover Robert D. Gibbons, R. Darrell Bock, Donald Hedeker, David J. Weiss, Eisuke Segawa, Dulal K. Applied Psychological Measurement 2007; 31; 4
In constructing scales to measure quality of life, investigators…have selected life satisfaction items from several domains ...
Although the instrument is designed to measure a single overall concept …
a result of the two-stage sampling procedure (i.e., domains within a construct and items within domains) frequently produces rating scales with a multidimensional structure.

23. Information Functions Bifactor Analysis: GHQ-28 NSHD

24. Analysed using ItemFA:ItemRT
Suite FA
Construct validity of a six-dimensional psychological well-being measure
42 items: self-report Qu.
Likert style responses
Item wording effects
Two method factors
Attempt to remove some nuisance covariance from similar response set to similarly worded items
Analysed using ItemFA:ItemRT

25. Psychometric evaluation and predictive validity of Ryff's psychological well-being items in a UK birth cohort sample of women.
Rosemary Abbott, George Ploubdis, Felicia Huppert, Diana Kuh, Michael Wadsworth and
Tim Croudace
Health and Quality of Life Outcomes 2006, 4:76
Free pdf online

26. Checklist… use c:\EGO_GHQ12_id.dta renvars recode order
corrtab ghq01-ghq09, spearman
genscore ghq*
corrtab ghq01 ghq03 ghq04 ghq07 ghq08 ghq12 score, spearman
corrtab ghq02 ghq05 ghq06 ghq09 ghq10 ghq11 score, spearman
Pcorr2
extremes
xsum
alpha , d c a l i s
cialpha
factor, ml fa(2)
Loadingplot
estat factors
rotate, bentler
estat rotatecompare
rotate,promaz
estat structure
Hangroot
Clv
sample 300, c su
keep ghq* id
use c:\EGO_GHQ12_id.dta
cfa1 ghq01-ghq12,unitvar
stata2mplus using c:\EGO_GHQ12_1234.for_ml_cfa1.dta
pca ghq*
predict pca1 pca2
multihist pca1 pca2
cfa1 ghq01-ghq12,unitvar vce(sbentler)
genscore ghq*, score(ghqsum)
runparscale ghq01-ghq12, id(id) runname(EGOGHQ121234n300)
multihist pca* *sum theta*
corrtab pca* *sum theta*
corrtab pca* *sum theta*, sig
polychoricpca ghq01-ghq12, nsco(2) score(pcpca)
corrtab ghqsum pca1 pcapca1 theta* cfa1score
corrtab ghqsum pca1 pcpca1 theta*
corrtab ghqsum pca1 pcpca1 theta*, sig obs
graph matrix ghqsum pca1 pcpca1 theta*