# types of data (ordinal, interval etc)

I have data from a questionnaire that uses likert scales only. The response options on the scale were regarding frequency, e.g. 'never' 'sometimes' and 'always'.

These responses were coded, with 'never' being given a 1, 'sometimes' being given a 2, and 'always' being given a 3. I understand that this is ordinal data as I used a likert scale.

However, I then summed all of the data up for the questionnaire by adding all of these coded values up for each question. So for example, if the questionnaire had 5 likert scales and someone answered all of them with the response of 'sometimes', then their answers would be coded as 2 and they therefore would have a total score of 10 for the questionnaire. Would this then become interval data or is it still somehow ordinal?

• For "likert" read "Likert" throughout. I think you can defend almost any answer. For example, as differences between ranks are no more than that, there are no grounds for regarding 2 + 2 = 1 + 3, etc. Hence there is no rigorous basis for any arithmetic manipulation and you can't even justify the result as ordinal. In practice, people do this because they hope that the ordinal grades are approximately numerical, so therefore a sum or mean is expected to be a good way of combining information. – Nick Cox Nov 2 '15 at 16:49
• Most university systems I've ever heard of do something equivalent with students' grades;meanwhile someone in a psychology department within probably explains at length every year to a small group of students that it is totally indefensible. I vote both ways. It's highly dubious in principle; in practice I would often try it and defend it as pragmatic if the results seemed to make sense. – Nick Cox Nov 2 '15 at 16:51
• There is a separate small terminology issue. Calling few-points scales Likert is regarded as unforgivably loose by those who know what he actually said. It's probably too late to reverse that except within certain fields. – Nick Cox Nov 2 '15 at 16:55