Hello!
I am having trouble constructing an ROC and getting Area under the ROC curve in SPSS. I'm hoping someone can help me.
I have a test that consists of ordinal data (1/8 codes, 2/8 codes, 3/8 codes, etc.) I want to see how many codes accurately diagnoses a disease.
When
I graph the sensitivies vs (1-specificities) in Prism and SAS, I get a
nice ROC curve, with AUROC 0.9618 (by Prism) and I can figure out the
cutoff. But, SPSS doesn't seem to graph it properly either when I make
a dataset with raw numbers - I manually created a dataset with columns of:
1) # of codes
2) Disease +/- (1/0)
I deleted all tests that were negative (since ROC curves only consist of TP and FP patients). When I run the ROC Curve in SPSS, it gives me a poor ROC with an AUROC of 0.68 - not at all what I get when I graph the ROC manually.
Any thoughts as to how I would set up my dataset to get the correct ROC?
Here is an example of my 2x2 tables:
1/8 codes:
Disease+/Test+ = 323
Disease+/Test- = 3
Disease-/Test+ = 91
Disease-/Test- = 102
Sens 99.08
Spec 52.85
PPV 78.02
NPV 97.14
2/8 codes:
Disease+/Test+ = 322
Disease+/Test- = 4
Disease-/Test+ = 69
Disease-/Test- = 124
Sens 98.77
Spec 64.25
3/8 codes:
Disease+/Test+ = 318
Disease+/Test- = 8
Disease-/Test+ = 47
Disease-/Test- = 146
Sens 97.55
Spec 75.65
4/8 codes:
Disease+/Test+ = 313
Disease+/Test- = 13
Disease-/Test+ = 37
Disease-/Test- = 156
Sens 96.01
Spec 80.83
etc etc. etc. through 5/8, 6/8, 7/8, 8/8
Thank you in advance!!
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