I just read your information in Sawtooth Software Forum about how to check for uncertainty of HB part worth utilities using a t-test. I am not sure if I did it the right way. This is how I did it:
1) I opened the alpha.csv output file and deleted the first 5.000 iterations. (Is this a good value to find convergenz?) Then I calculated the standard deviation of every part worth utility using the remaining 15.000 iterations. (s.d. = 0.36)
2) Then I calculated the S.E.=0.36/(15.58) --> n=243; S.E.=0.0231
3) Afterwards I sorted those 15.000 iteration of the part worth utility in an histogram to find values for the 95% confidence interval (which are the alpha values of 2.5 and 97.5 in the histogram).
4) Finally I calculated the t-value: “Average Utility” value = -11.61/0.0231=-504.53 (-11.61=“Average Utility” value from the report.xls file). When my the two alpha-values are -1.11 and 0.31, my t-value is outside this range and is significant.
Could you tell me if this is the right way?
Thank you very much!