Date:         Sun, 11 Sep 2005 11:02:59 -0400
Reply-To:     Art@DrKendall.org
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Art Kendall <Art@DrKendall.org>
Organization: Social Research Consultants
Subject:      Re: improving reliability
Comments: To: gokhan kaya <kayagk@yahoo.com.ar>
In-Reply-To:  <20050911114207.17483.qmail@web52810.mail.yahoo.com>
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Were the items designed to measure particular constructs?
What are they?  How many items did you have for each potential scale?
  How did you get the items? Did you use pre-existing scales?

starting with all of the items, do a PA2 factor analysis, see if it
suggests that the number of factors to extract is about the number that
you intended to have scales for.

Be sure that items are reflected as necessary to to assure that a high
item score indicates the direction of a high scale score.

Then do reliability with the set of items that are indicated to go together.

Do you have at least 4 and preferably more items on each proposed scale?

Art
Art@DrKendall.org
Social Research Consultants
University Park, MD  USA
(301) 864-5570

gokhan kaya wrote:

>Dear All
>
>To imprrove reliability (Conchran alpha) what should I do?
>I started with removing some items  becuse of larger values in the column of  alpha if item is deleted
>and use factor analysiss to reduce data
>Finally, these results make me to remove some items but this efforts still not neough since conchran alpha is increased from 0.32 to 0.47 but it is under the level of 0.6.8 (common use)
>and I've also another problem:
>My questionnaire is applied in two similar qualified(similar socio economic status) provinces but  one of them reveal much smaller alpha values  than another one for 3 scales.
>Are there alternative way to improve alpha values?
>What is the source of this difference between two porvinces and howcan I overcome it?,
>If I can
>
>Any helps and recommendetions are appreciated
>Thanks Advance
>BESTS
>Gokhan KAYA
>
>
>
>
>
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