GHQ-12 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 INSTRUCTIONS We should like to know if you have any medical complaints, and how your health has been in general, over the past few weeks….. We want to know about present and recent complaints, not those you had in the past.

12 item GHQ (6 positive items) able to enjoy day-to-day activities More so than usual MSTU Same as usual SAU Less so than usual LSTU Much less than usual MTLU Item 8 able to face up to your problems Less able than usual LATU Item 12 feeling reasonably happy all things considered Item 1 able to concentrate Better than usual BTU Same as usual SAU Less than usual LTU Much less than usual MTLU Item 3 playing a useful part More so than usual MSTU Less useful than usual LUTU Item 4 felt capable of making decisions Less so than usual LSTU Much less capable MLC

12 item GHQ (6 negative items) feeling unhappy and depressed Not at all NAA No more than usual NMTU Rather more than usual RMTU Much more than usual MMTU Item 10 been losing confidence in yourself Item 11 thinking of self as worthless person Item 2 lost much sleep over worry Not at all NAA No more than usual NMTU Rather more than usual RMTU Much more than usual MMTU Item 5 playing a usefu part Item 6 felt capable of making decisions

ILLEGAL & WRONG !!!

Goldberg’s GHQ-12: BHPS VARIABLE & RESPONSE LABELS ighqa : ghq: concentration 1: better than usual 2: same as usual 3: less than usual 4: much less thn usual ighqb : ghq: loss of sleep 1: not at all 2: no more than usual 3: rather more thn usul 4: much more than usual ighqc : ghq: playing a useful role 1: more than usual 3: less so 4: much less ighqd : ghq: capable of making decisions ighqe : ghq: constantly under strain 3: rather more 4: much more ighqf : ghq: problem overcoming difficulties ighqg : ghq: enjoy day-to-day activities 1: more than usual 2: same as usual 3: less so 4: much less ighqh : ghq: ability to face problems ighqi : ghq: unhappy or depressed 1: not at all 2: no more thn usual 3: rather more 4: much more ighqj : ghq: losing confidence 2: no more than usual ighqk : ghq: believe in self-worth ighql : ghq: general happiness

Duncan-Jones et al (1986), Psych Med Goldberg et al (1987) Psych Med Latent Goldberg: What kinds of models are required to ask what research questions? Q … the characteristics and performance of GHQ items as measures of distress, and the estimated or assumed dist’n of the latent trait Q … the potential for some items to be scored to capture a notion of positive mental health. Does the GHQ “do” well-being? Psychiatry Psychology Focus on negative items Normal ogive item response models WLS Logistic distribution item response models ML Focus on GHQ positive items Equal interval scoring as 2-1-0-0 Interval? Coding “more than usual” 1-0-0-0 + ve items Latent variable model (IRT/LTA or CDFA) Discrimination & Difficulty params ICCs Information function (effective measurement) Scoring methods for -ve items (cGHQ) Model-based vs simple sum score (linear models, interval (metric) scores) Person (cluster) vs variable centered analyses IRT models with ordinal or nominal indicators Standard statistical approach - under applied Novel scoring approaches, under-validated Duncan-Jones et al (1986), Psych Med Goldberg et al (1987) Psych Med Whittington & Huppert (2003) SSM Ploubidis et al (2007) P&ID

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

Setting the scene Software use: what do you use? SPSS SAS STATA R/Splus MATLAB Specialist: Psychometric BILOG MULTILOG TESTFACT PARSCALE Rasch software

Psychometric papers What statistics/statistical analyses do you associate with a “psychometric” paper What would you use a computer to calculate for you? Why are you doing that? Why only that? What else could you do and how? Increasing your options and understanding of the range of psychometric scaling approaches and statistic analyses Psychometric analyses, and increasing the accuracy with which you describe, execute and combine them

Example: GHQ General Health Questionnaire See GHQ Users Guide and Goodchild-Duncan Jones (Ref pdf) This instrument has no numbers on it Scoring begins from assignment of 1, 2, 3, 4 (weights) i.e. consecutive integers to the ordered levels of the graded responses [Scoring methods alter weights/Scaling models estimate weights] Be careful with question wording GHQ is balanced in terms of + & - question wording [what does this mean?] Why – and what implication(s)? NB: If response options are consistently (re)-worded, this avoids the need for reverse scoring]

GHQ-30 data from a population survey: HALS (Baseline)

GHQ-30 data from a population survey: HALS (9 items)

New portable C:\HALS_CGHQ_negativeonly.dta

Time to share out well tested Data preparation pipeline (semi-automated) Take it away Jon