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Thread: Low Cronbach alpha on recognised instrument

  1. #16
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    Re: Low Cronbach alpha on recognised instrument




    I would still report the alpha in the dissertation, otherwise you are just limiting the readers knowledge. Every instrument performs differently in every sample and everyone implements protocols differently. If your alpha is different that could just be the way it is as well with or without systematic error.
    Stop cowardice, ban guns!

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    JakeMac (03-13-2013)

  3. #17
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    Re: Low Cronbach alpha on recognised instrument

    Quote Originally Posted by JakeMac View Post
    The reliability of the OCQ was tested in a meta-analysis by Meyer, Stanley, Herscovitch, & Topolnytsky (2002) with 15 years of OCQ questionnaire results using both the 24 item and 18 item versions of the OCQ. They found the reliability of the OCQ to be .82 for affective commitment, .73 for continuance commitment, and .76 for normative commitment.
    I've had a very quick look at the paper. It doesn't really matter much, but don't you have the continuance commitment and normative commitment reliabilities around the wrong way? I read the paper as saying .76 for continuance commitment. They don't seem to say what kind of reliability estimates they're talking about, so presumably the meta-analysis is based on a hodgepodge of Cronbach's alpha, test-retest, split half and other reliability estimates.

    Most psychometricians view reliability as a property of data, not of an instrument. So the test could well produce "reliable" measurements in some samples, but not in yours, meaning that probably the estimate in your own data is the one that matters most.

    But see the excellent article Lazar posted about the limitations of alpha.

    Quote Originally Posted by JakeMac View Post
    My question is simple, do I disregard the 0.51 as the instrument has been proven already, or do I remove it from the study and explain due to the 0.51 alpha that I have excluded it from any further correlations etc.
    Avoid the word "proven" when you're talking about empirical research. Proofs are in maths and logic, not empirical science.

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    JakeMac (03-13-2013)

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    Phineas Packard
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    Re: Low Cronbach alpha on recognised instrument

    I still think SEM is a possible way forward. As measurement error is directly estimated resulting parameter estimates based on the underlying latent are unbiased to said measurement error. Thus a low reliability is less of a problem.

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    JakeMac (03-13-2013)

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    Re: Low Cronbach alpha on recognised instrument


    Ok gents, thanks a lot for the all your time and assistance. As I have mentioned I'm a bit out of my depth here. O.76 was the CCS, my mistake. The values I have put up are the Guttman Lower Bound values for the six items calculated on SPSS 20 and have confirmed these by viewing the help topics in spss. Does this help? I am really trying to do well on the dissertation, so I want to make sure nothing I do is wrong. Is it fair to say ( unless the glb can be included and helps the situation) that I could eliminate the continuance commitment element from the rest of the research based on the low cronbach alpha that I have attained for my data in that particular aspect. Is this too bold or would other authors have done this? I understand the article about use and misuse of cronbach but for an undergraduate degree dissertation I don't think they can pull me up too much by not going further with it? So if I summarise, and please comment on this, I have used a standard recognised instrument, but for my particualr study one aspect/grouping have returned a lower than acceptable cronbach alpha. Therefore I have decided to remove this aspect/group from the remainder of the research due to this fact. If I go a bit further and include the glb and say that this too has yielded low result confirming that the aspect/group is unreliable for the rest of the study? (of course I'm presuming you need a glb of over .7 too, which could be completly wrong?) HELP. I have to have a draft of this done by saturday night and this has become a sticking point that is getting more time than I hoped.

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