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Fluorite | Level 6

## How to understand the ODS output table ItemInfoCurve in PROC IRT ?

When I specify

`ods output IRT.ItemInfo.ItemInfoCurve=II;`

the output data set seems to be stacked (~100 lines per item), but with no indication about which item provides which values ?

1 ACCEPTED SOLUTION

Accepted Solutions
SAS Super FREQ

## Re: How to understand the ODS output table ItemInfoCurve in PROC IRT ?

You are correct: that output is unclear and difficult to work with.

By looking at the output data, you can see that each curve is represented by 101 points. Therefore if you create a new variable PlotNum=ceil(_N_/101), you will correctly identify the curves.

Here is an example that uses the data in the Getting Started example in the PROC IRT documentation:

``````proc irt data=IrtBinary plots(unpack)=IIC;
var item1-item10;
ods output ItemInfoCurve=II_0;
run;

data II;
set II_0;
PlotNum = ceil(_N_ / 101);
run;

proc sgpanel data=II;
panelby PlotNum / columns=3 rows=2;
series x=Trait y=ItemInfo;
run;``````

SAS Super FREQ

## Re: How to understand the ODS output table ItemInfoCurve in PROC IRT ?

You are correct: that output is unclear and difficult to work with.

By looking at the output data, you can see that each curve is represented by 101 points. Therefore if you create a new variable PlotNum=ceil(_N_/101), you will correctly identify the curves.

Here is an example that uses the data in the Getting Started example in the PROC IRT documentation:

``````proc irt data=IrtBinary plots(unpack)=IIC;
var item1-item10;
ods output ItemInfoCurve=II_0;
run;

data II;
set II_0;
PlotNum = ceil(_N_ / 101);
run;

proc sgpanel data=II;
panelby PlotNum / columns=3 rows=2;
series x=Trait y=ItemInfo;
run;``````

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