[IPAC-List] Reliability for T&Es

[Bryan Baldwin]

Thanks for the responses.  To be honest, I am the beginning of investigating this issue, and the type of T&Es I'm thinking of are primarily task-based.  For those of us in a civil service system where banding is mandatory, the increasing use of T&Es begs the question of how these bands should be formed.  I suspect in many cases it's done simply by dividing the raw spread by the number of ranks.  To speak to Dennis' question, I have also suspected the bands should be quite large, particularly at the top given inflation tendencies.  Of course the pass point obviously plays an issue here, and in my experience SMEs tend to want to set a higher pass point than is really necessary, which plays into the size of the bands.
 
Dan, I appreciate your questions.  As for how I'm defining error, I'm slightly more concerned about internal consistency than I am about test-retest, but in reality most concerned about the accuracy of ratings.  What makes this even more complicated is the quality of the T&E items and scales themselves vary dramatically, much more so than your typical m-c item.
 
To answer your second question, a single overall score is being generated.  I have zero faith in the ability of these exams to measure separate distinct constructs.
 
BB


>>> <dputka at humrro.org> 6/22/2010 7:06 AM >>>

Hi Bryan,

A few questions....

1. How are you defining error for your T&E measure?

a. As inconsistency across items?   In other words, do you want to draw
inferences with regard to the consistency in your T&E scores if they were
based on different sampling of items?

b. As inconsistency across occasions?  In other words, do you want to draw
inferences with regard to the consistency in your T&E scores if respondents
completed your measure on a different occasion?

c. Are you concerned about both types of inconsistency referenced above?


2. What is the substantive nature of your T&E measure?

a. Are you trying to assess multiple, distinct constructs with your T&E
measure (e.g., each construct indicated by a subset of items comprising the
T&E measure)?

b. Or, do you simply have an overarching, heterogenous measure of T&E?

Depending on how you define error (which is a function of the inferences
you want to make with regard to the consistency of your scores), and the
substantive nature of your T&E measure, it will dictate the structure of
the reliability coefficient that is most appropriate for your situation.

For a general discussion of this, see:
Putka, D. J. & Sackett, P .R. (2010).  Reliability and validity. In J.L.
Farr, & N.T. Tippins (Eds.). Handbook of Employee Selection (pp. 9-49). New
York: Routledge.


Hope this helps,

Dan


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Dan J. Putka, Ph.D.
Principal Staff Scientist
Personnel Selection & Development Program
Human Resources Research Organization (HumRRO)
66 Canal Center Plaza, Suite 700
Alexandria, VA  22314-1591
703-706-5640 (o)
703-548-5574 (f)
http://www.humrro.org 
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From:"Bryan Baldwin" <Bryan.Baldwin at doj.ca.gov>
To:ipac-list at ipacweb.org 
Date:06/21/2010 07:05 PM
Subject:[IPAC-List] Reliability for T&Es
Sent by:ipac-list-bounces at ipacweb.org 



Can anyone point me to a source for how to compute reliability for T&Es
(assuming it can be done)?  Ultimate goal is to use this to create bands.

Thanks-

Bryan Baldwin
Staff Services Manager II
California Department of Justice
Division of Administrative Support
Personnel Programs
(916) 322-5446


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