The control compared to treatment group 2 (who saw day affect information) I find that the proportional odds assumption is not violated when I look at preference (1st, 2nd, 3rd preference) for anxiety/depression (which is my main interest) and not violated for self-care and for pain but are violated when look at preferences for pain (although violation doesn’t seem to be on the information provision variable.
Before I tested the assumption the results of the ordered logit indicate that co-efficient on INFO is significant and negative for anxiety/depression, is significant and positive for self-care and non-significant for pain.
I am unsure what to conclude about the proportional odds assumption? Details are below.
Prediction: Provision of information on the association of health states with SWB to participants before they appraise health states will result in a lower preference for anxiety/depression than other health states.
Experiment A randomized control trial in which the control group judges the health states as normal, one treatment group judges the health states after provision of information on the association of the health states with life satisfaction and the second treatment group judges the health states after provision of information on the association of the health states with day affect.
Choice: Participants are provided with a description of some problems with self-care, moderate pain/discomfort and moderate anxiety/depression. Participants made a choice between health states, from most to least preferred to live in by entering 1 for most preferred, 2 for second preference and 3 for third preference.
Model: The dependent variable is an ordered outcome variable so choices are examined using an ordered logit (ordered probit) model of the form in Equation 1.
P (Cj) = β0 + β1INFO i + β2DEMOi + β3EMPLOYi + β4HEALTHi + β4LSi + εi
Output of brant test is shown below; first for LS and then for DA.
DA Info | ANXIETY/DEPRESSION | LS info | ANXIETY/DEPRESSION | |||||
chi2 | p>chi2 | df | chi2 | p>chi2 | df | |||
All | 14.61 | 0.201 | 11 | All | 7.54 | 0.754 | 11 | |
1.groupdum | 0 | 0.979 | 1 | 1.groupdum | 0.03 | 0.853 | 1 | |
2.sex | 0.34 | 0.562 | 1 | 2.sex | 1.5 | 0.22 | 1 | |
age | 0.02 | 0.901 | 1 | age | 1.58 | 0.209 | 1 | |
agesqu | 0.14 | 0.708 | 1 | agesqu | 1.5 | 0.221 | 1 | |
1.reldum | 0.02 | 0.888 | 1 | 1.reldum | 0.9 | 0.342 | 1 | |
1.mainactdum | 0 | 0.97 | 1 | 1.mainactdum | 0 | 0.97 | 1 | |
1.highedudum | 2.9 | 0.089 | 1 | 1.highedudum | 0.1 | 0.754 | 1 | |
2.highedudum | 6.78 | 0.009 | 1 | 2.highedudum | 2.36 | 0.124 | 1 | |
3.highedudum | 2.2 | 0.138 | 1 | 3.highedudum | 0.1 | 0.752 | 1 | |
yourhealthvas | 0.4 | 0.527 | 1 | uvas | 0.5 | 0.482 | 1 | |
ls | 2.75 | 0.097 | 1 | ls | 0.85 | 0.356 | 1 | |
DA Info | SELF CARE | LS Info | SELF CARE | |||||
chi2 | p>chi2 | df | chi2 | p>chi2 | df | |||
All | 18.48 | 0.071 | 11 | All | 20.8 | 0.035 | 11 | |
1.groupdum | 0.07 | 0.799 | 1 | 1.groupdum | 2.14 | 0.143 | 1 | |
2.sex | 0.71 | 0.401 | 1 | 2.sex | 6.47 | 0.011 | 1 | |
age | 0.9 | 0.344 | 1 | age | 1.41 | 0.234 | 1 | |
agesqu | 1.55 | 0.214 | 1 | agesqu | 1.01 | 0.315 | 1 | |
1.reldum | 0.27 | 0.603 | 1 | 1.reldum | 0.08 | 0.773 | 1 | |
1.mainactdum | 1.34 | 0.246 | 1 | 1.mainactdum | 1.97 | 0.161 | 1 | |
1.highedudum | 0.22 | 0.64 | 1 | 1.highedudum | 3.47 | 0.062 | 1 | |
2.highedudum | 1.06 | 0.304 | 1 | 2.highedudum | 0.67 | 0.415 | 1 | |
3.highedudum | 0.01 | 0.919 | 1 | 3.highedudum | 2.61 | 0.106 | 1 | |
yourhealthvas | 0.01 | 0.93 | 1 | uvas | 0.11 | 0.741 | 1 | |
ls | 2.13 | 0.144 | 1 | ls | 4.74 | 0.029 | 1 | |
DA Info | PAIN | LS Infor | PAIN | |||||
chi2 | p>chi2 | df | chi2 | p>chi2 | df | |||
All | 22.22 | 0.023 | 11 | All | 20.8 | 0.035 | 11 | |
1.groupdum | 1.78 | 0.183 | 1 | 1.groupdum | 2.14 | 0.143 | 1 | |
2.sex | 0.42 | 0.519 | 1 | 2.sex | 6.47 | 0.011 | 1 | |
age | 0.01 | 0.913 | 1 | age | 1.41 | 0.234 | 1 | |
agesqu | 0.13 | 0.718 | 1 | agesqu | 1.01 | 0.315 | 1 | |
1.reldum | 0.09 | 0.762 | 1 | 1.reldum | 0.08 | 0.773 | 1 | |
1.mainactdum | 3.02 | 0.082 | 1 | 1.mainactdum | 1.97 | 0.161 | 1 | |
1.highedudum | 0.02 | 0.895 | 1 | 1.highedudum | 3.47 | 0.062 | 1 | |
2.highedudum | 0.21 | 0.65 | 1 | 2.highedudum | 0.67 | 0.415 | 1 | |
3.highedudum | 0.14 | 0.711 | 1 | 3.highedudum | 2.61 | 0.106 | 1 | |
yourhealthvas | 0.53 | 0.468 | 1 | uvas | 0.11 | 0.741 | 1 | |
ls | 5.3 | 0.021 | 1 | ls | 4.74 | 0.029 | 1 |
0 Response to Brant tests: What should I conclude from Brant tests about the proportional odds assumption of ordered logit as the results conflict?
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