Comparing Likert scales of different lengths

#1
Hi there talkstats experts. For my thesis I am doing research about listener's attitudes towards 4 different Dutch accents. Next to that I also do research about the lengths of Likert scales. I did 2 surveys with the same questions but one with a likert scale length of 6 and one of 7 answer options. I'd like to compare the 2 in a statistical useful way. Also, statistics isn't my strength. I use SPSS. What do you guys think that I should do?


(My solutions are: -Multiplying the answers of the 6 scale survey by 7, and the 7 scale survey by 6. This might be hard to defend, given that the intervals between the answer options weren't the same to begin with. -Using z-scores to compare the two surveys. This is quite helpful, and both my survey answer data show quite a high degree of normality. But I cannot really tell which survey of the 2 gets rated the highest, for example.)
 

MrJP

New Member
#2
Personally I would have divided the 6-point scale by 6 and multiplied it with 7 to compare the scales, but your solution by multiplying both should lead to the same results. That the intervals aren't that same is one of the differences between the scales, so I do not think this has to be a problem. This can be an explanation of any found differences.

Additionally I would also explore in the differences in distribution, variance & standard deviation and number of outliers (altough it's difficult to speak of outliers on such small scales). For more idea's you could look into data exploration methods, or maybe even (confirmatory) factor analysis.