Week 7: Reliability, Validity, & Utility Flashcards
Find the magnitude of error and develop ways to minimize them
Presence of Error
Tests that are relatively free from measurement error are deemed to be…
reliable
Less error =
High validity
Error exists because we only obtain a sample of..
behavior
who pioneered reliability assessment?
Charles Spearman
other pioneers
– De Moivre
– Pearson
– Kuder and Richardson
– Cronbach
CTT: 𝑋 =
𝑇 + E
Measuring instruments are ____
imperfect
observed score is almost always different from the ____ ability/characteristic
true
____ of measurement are random
Errors
Because of random error, repeated application produces…
different results
Problem created by using a limited number of items to represent a larger, more complicated construct
Domain Sampling Model
Task in reliability analysis is to estimate how much ______ is made by using a test score from the shorter test as estimate of the true ability
error
the ratio of variance of the observed score on the shorter test and the variance of the long-run true score
Reliability
Reliability can be estimated by ______ the observed score with the true score
correlating
T is not available so we estimate what ___
they would be
To estimate reliability, we create many randomly _____
paralleled test
focuses on an item difficulty to assess the ability
Item Response Theory
Parelleled Tests are the same tests measuring…
the same concepts
Reliability is related to…
consistency
Reliability Coefficient
is an index of reliability, a proportion that indicates the ratio between the true score variance on a test and the total variance
is 0.7 an accepted coefficient?
yes
what coefficient cannot go beyond?
beyond 0.95
what is the critical coefficient?
0.6
What are sources of error?
- Test Construction
- Test Administration
- Test Scoring and I
What is under Test Construction?
Item sampling; content sampling
an estimate of reliability obtained by correlating pairs of scores from the same people on two different administrations of the same test
Test-Retest Reliability Estimate
When the interval between testing is greater than six months, the estimate of test-retest reliability is often referred to as the coefficient of…
stability
exist when, for each form of the test, the means and the variances of observed test scores are equal
Parallel forms
simply different versions of a test that have been constructed so as to be parallel
Alternate Forms
coefficient of equivalence
Parallel-Forms and Alternate-Forms Reliability Estimates
obtained by correlating two pairs of scores obtained from equivalent halves of a single test administered once
Split-Half Reliability Estimates
What is the correct order for split-half?
a. Calculate a Pearson r between scores on the two halves of the test.
b. Divide the test into equivalent halves.
c. Adjust the half-test reliability using the Spearman-Brown formula
b-a-c
refers to the degree of correlation among all the items on a scale
Inter-item consistency
A measure of inter-item consistency is calculated from _____ of a single form of a test
a single administration
measures a single trait
Homogenous Test
The more homogenous the test is, the better the…
internal consistency
Where test items are highly homogeneous, KR20 and split-half reliability estimates will be similar.
Kuder-Richardson formulas
is the statistic of choice for determining the inter-item consistency of ______, primarily those items that can be scored right or wrong (such as multiple-choice items).
dichotomous items
If test items are more ______, KR20 will yield lower reliability estimates than the split-half method.
heterogeneous
Dichotomous items include 3 or more choices
False, it only includes 2 choices (i.e., yes or no, true or false)
rKR20 stands for?
Kuder-Richardson formula 20 reliability coefficient
k is the…
number of test items
σ2 is the…
variance of total test scores
p is the proportion of test takers who…
pass the item
q is the proportion of people who…
fail the item
Σ pq is the sum of the pq products…
over all items
the mean of all possible split half correlations, corrected by the Spearman-Brown formula
Coefficient Alpha
are coefficient alpha items also dichotomous?
no, they are non dichotomous items