Adjusting Likert Item Scoring After Finding Very Low Reliability
A Story by Larry Nelson, Curtin University

18 August 2010

The data are from the administration of a 48-item attitude scale. All items used a 1 – 5 Likert scale, with 5 = “strongly agree”.

The original control “cards” used by an overhasty graduate student:

The reliability was terrible (especially as this was a well-known affective scale)!

Several items had negative correlations:

The bottom of the Stats1f report was revealing:

The IStats results were even more revealing (note negative p-comp1 loadings) :

Larry’s new CCs lines in green (note the *pol line):

Vastly-improved reliability noted:

No negative correlations now (note the pol. column):

The bottom of Stats2f was better than Stats1f:

The new IStats report was much better (note movie shows how to get IStats):

What the overhasty graduate student had overlooked:

Many of the items in the scale were negatively-worded. For example, the sample item shown on line 12 above (item “14”) should be reverse-scored. The graduate student had simply failed to use a *pol line to correct the scoring for those scale items which were negatively-worded.

Addendum:

A scree plot is easy to get (note movie shows how):

There are a few System settings which are relevant:

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