James:
Using "?" is not good. "Neither Agree Nor Disagree" would be better. "?" will
end up being a catch-all response: for those who neither agree nor disagree, those
who didn't understand the question, who choose not to answer the question, and so
forth. In which case the resultant numbers will have more error. It can confound
comparisons between items. Let's say you had two questions, both of which a
majority of respondants agree with to the same amount - but one question is more
difficult to understand. Respondants who are otherwise inclined to skip the item
may choose "?" instead. If you code the responses 1 to 5, the median or mean
response will be higher on the more incomprehensible question; you may misinterpret
this to mean respondants agreed with it less than the other question.
Some people avoid an odd number of points to avoid the problem. Having a 4 or 6
point scale forces respondants to choose between the agree and disagree side. This
can increase validity in some cases. When threatening or uncomfortable questions
are asked, respondants will seek the neutral ground on the scale. For instance take
the item "Very sick people are better off dying than prolonging their agony" A
respondant may lean towards agree, but may be uncomfortable admitting it and seek
the "Neither" option. Depriving them of the center point will increase the validity
of the scale, forcing (or nudging) them to fess up with their reply.
[EMAIL PROTECTED] wrote:
>
> I need some professional advice on a statistics question. I recently took part
> in a survey where the scale of responses was given as:
>
> Agree / Tend to Agree / ? / Tend to Disagree / Disagree
>
> The question mark in the middle seems very ambiguous to me. Can anyone tell me
> if this is a commonly used scale, and if so, what is the question mark supposed
> to mean?
--
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John W. Kulig [EMAIL PROTECTED]
Department of Psychology http://oz.plymouth.edu/~kulig
Plymouth State College tel: (603) 535-2468
Plymouth NH USA 03264 fax: (603) 535-2412
---------------------------------------------------------------
"What a man often sees he does not wonder at, although he knows
not why it happens; if something occurs which he has not seen before,
he thinks it is a marvel" - Cicero.
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