Dear statalisters,
I checked my probit model by applying the percent correctly predicted method for its goodness-of-fit. Here is what I got:
Probit model for atrisk_only
-------- True --------
Classified | D ~D | Total
-----------+--------------------------+-----------
+ | 1 1 | 2
- | 245 2474 | 2719
-----------+--------------------------+-----------
Total | 246 2475 | 2721
Classified + if predicted Pr(D) >= .5
True D defined as atrisk_only != 0
--------------------------------------------------
Sensitivity Pr( +| D) 0.41%
Specificity Pr( -|~D) 99.96%
Positive predictive value Pr( D| +) 50.00%
Negative predictive value Pr(~D| -) 90.99%
--------------------------------------------------
False + rate for true ~D Pr( +|~D) 0.04%
False - rate for true D Pr( -| D) 99.59%
False + rate for classified + Pr(~D| +) 50.00%
False - rate for classified - Pr( D| -) 9.01%
--------------------------------------------------
Correctly classified 90.96%
It seems that my model is good in predicting when y=0 (what is not a surprise, since in most cases of my sample y=0), but fails to predict when y=1.
Is it correct to take this as a sign that my model does not have a good fit? What could I do to improve my model? Are there other goodness-of-fit measures that might be more suitable for my case?
Thank you in advance!
Best Jan
I checked my probit model by applying the percent correctly predicted method for its goodness-of-fit. Here is what I got:
Probit model for atrisk_only
-------- True --------
Classified | D ~D | Total
-----------+--------------------------+-----------
+ | 1 1 | 2
- | 245 2474 | 2719
-----------+--------------------------+-----------
Total | 246 2475 | 2721
Classified + if predicted Pr(D) >= .5
True D defined as atrisk_only != 0
--------------------------------------------------
Sensitivity Pr( +| D) 0.41%
Specificity Pr( -|~D) 99.96%
Positive predictive value Pr( D| +) 50.00%
Negative predictive value Pr(~D| -) 90.99%
--------------------------------------------------
False + rate for true ~D Pr( +|~D) 0.04%
False - rate for true D Pr( -| D) 99.59%
False + rate for classified + Pr(~D| +) 50.00%
False - rate for classified - Pr( D| -) 9.01%
--------------------------------------------------
Correctly classified 90.96%
It seems that my model is good in predicting when y=0 (what is not a surprise, since in most cases of my sample y=0), but fails to predict when y=1.
Is it correct to take this as a sign that my model does not have a good fit? What could I do to improve my model? Are there other goodness-of-fit measures that might be more suitable for my case?
Thank you in advance!
Best Jan
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