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Jack2012
Obsidian | Level 7

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Dear All,

 

I am using PROC FREQ to get the proportion of discordant pairs and its 90% Confidence interval. However, I found one special case when the Binary response all equal to 1, then there is no report on the ODDS ratio, Gamma, etc.

 

Anybody can help me to figure out this? To my understanding, if all binary Response equal to 1, then the Gamma value should be 1.

Many thanks for your help to me on this.

proc freq data=dar_s order=data;  
	tables drgdsc1a* SWAEVL2C/measures CL;
run;
1 ACCEPTED SOLUTION

Accepted Solutions
Rick_SAS
SAS Super FREQ

These measures of association are defined for ordinal variables in two-way tables. From the doc: "A pair is concordant if the observation with the larger value of X also has the larger value of Y."  (X=row variable; Y=column variable)

 

In your example, the Y variable has only one value. There is no "larger value of Y" to use to define pairs as condordant or discordant. Thus any formula that uses "number of condordant pairs" is undefined.

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5 REPLIES 5
Rick_SAS
SAS Super FREQ

Check the log. Is there a NOTE that says:


NOTE: No statistics are computed for drgdsla *  SWAEVL2C because SWAEVL2C has less than 2 nonmissing levels.

Rick_SAS
SAS Super FREQ

These measures of association are defined for ordinal variables in two-way tables. From the doc: "A pair is concordant if the observation with the larger value of X also has the larger value of Y."  (X=row variable; Y=column variable)

 

In your example, the Y variable has only one value. There is no "larger value of Y" to use to define pairs as condordant or discordant. Thus any formula that uses "number of condordant pairs" is undefined.

Jack2012
Obsidian | Level 7

Dear Rick,

 

You ansswered my question perfectly. I understand the "concordant and discordant" more clearly with you post.

 

Best,

Jack

Ksharp
Super User

As Rick pointed out, you can't get Gamma due to there is only one level(value 1) of SWAVEL2C.
Gamma measure the correlation between row variable and col variable, so you can't get it if col variable only have one level.

Jack2012
Obsidian | Level 7

Great thanks, got now.

 

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