2. Four different reasons why one will find two factors for a one dimensional concept

3. Measurement of an attitude towards environmental protection One can ask questions like: -To what extent do you support environmental protection? -To what extent are you interested in these problems? -Do you give money for these issues? -To what extent do you agree that money is given for this goal? -Did you even give money for this problem?

4. The simplex structure These questions can be ordered Y1=Interest Y2=Positive Y3=Agree with support Y4=Gave support Y5= Gives regular support There is an order from weak to strong support

5. Two factors for unidimensional scales Guttman (1956) suggested that not all sets of questions should be analyzed by factor analysis There are data which have been produced by another model than a factor model In that case one will derive wrong conclusions In case of a simplex structure one will detect two factors for the one dimensional attitude: a high and a low factor

6. ESS round 3; feelings of Wellbeing

7. The original and reordered correlation matrix

8. The factor analysis With one factor model (N=2220) chi2 = 1041 df=9 RMSEA =.23 Many misspecifications suggested by JRule With a two factor model Chi2 = 128 df= 8 RMSEA =.08 No misspecifications suggested by JRule

9. Normal conclusion Two factor solution: One for the positive items One for the negative items However I think that the model is wrong and that the items are unidimensional

10. The topic of the seminar Besides the Simplex model we will present here three other explanations for the two factor solution for a unidimensional set of items Akos Munnich and Wijbrandt van Schuur will present substantive models I will present a methodological argument

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