Validating scales and indexes guardian dating manchester
Three quarter of the items is a reasonable minimum value – e.g.
You can determine with a point behind the MEAN ()-command, that a minimum number of responses per case have to be present. The more scale items are used to measure the construct, the more accurate is the measurement, because measurement errors for individual items will be less important. Therefore a scale is often used for measurement in questionnaires: Several separate questions – known as scale items – that all represent different aspects of the same construct.Therefore some items have a stronger impact on the scale index than others.
Whether this is favorable or not depends on the scale.
A z-standardization is especially beneficial if you there are missing values in the data.