# How do I create a composite with items with different scale ranges?

(Difference between revisions)
 Revision as of 03:10, 25 May 2008 (view source)Doug (Talk | contribs)← Older edit Revision as of 03:20, 25 May 2008 (view source)Doug (Talk | contribs) Newer edit → Line 1: Line 1: - + '''How do I create a composite with items with different scale ranges?''' - + *If you are going to composite together multiple items, all the items need to have the same scale range. Why? Lets say we ask two happiness questions: (1) "How happy are you right now?" on a 1-7 scale, and (2) "How happy do you feel?", on a -3 to 3 scale. Notice that the two questions are about the same construct (so theoretically you can merge them together), and also notice that the total range of the scales for both items are 7 points, BUT the scale ranges are along different dimensions. Compositing involves averaging items together. If we average together these two items, the resulting average will not be interpretable because of the different scale ranges. [[Image:Fe40.png]] - A "1" on the first item is the lowest possible answer choice, but a "1" on the second item is one of the highest possible choices. + *The solution is to transform both scale ranges into a common metric. This is accomplished by first “standardizing” both items. Then, you composite the newly transformed items. +

## Revision as of 03:20, 25 May 2008

How do I create a composite with items with different scale ranges?

• If you are going to composite together multiple items, all the items need to have the same scale range. Why? Lets say we ask two happiness questions: (1) "How happy are you right now?" on a 1-7 scale, and (2) "How happy do you feel?", on a -3 to 3 scale. Notice that the two questions are about the same construct (so theoretically you can merge them together), and also notice that the total range of the scales for both items are 7 points, BUT the scale ranges are along different dimensions. Compositing involves averaging items together. If we average together these two items, the resulting average will not be interpretable because of the different scale ranges. - A "1" on the first item is the lowest possible answer choice, but a "1" on the second item is one of the highest possible choices.
• The solution is to transform both scale ranges into a common metric. This is accomplished by first “standardizing” both items. Then, you composite the newly transformed items.

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