Hello,
I am using a pre-existing universal tested scale to measure a specific construct. The construct is measured through 5 items on a 5 points likert scale. However, I would probably need to change the range of all the items scale from 5 to 7. Would this affect in any way the validity and reliability of the construct?
In fact, I keep seeing researchers changing the points range of items for their own purposes. However, I am not sure whether this would affect in any way the reliability or validity of the scale. Indeed I have been told that this practice is wrong and would negatively affect my analysis. Yet, sometimes I see researchers using even smaller version of the same scale with less items. If that is fine I could possibly changing the point range affect validity and reliability of the scale?
Thank you!
Both reliability and validity are assessed by patterns of correlations among variables, so anything that affects how a variable correlates with other variables could have an impact on reliability and validity. But "could have an impact" is not a very strong standard, and the available research indicates it is unlikely that changing from a 5-point to a 7-point format would make much difference in the overall reliability and validity of a scale.
Dear Prof. David Morgan,
thank you for your reply.
Is there any rerence I can use to support that?
Thank you again,
Eleonora
Here is an article by two well-known experts in the field, which could have some useful information.