Page 374 - DEDU504_EDUCATIONAL_MEASUREMENT_AND_EVALUATION_ENGLISH

Educational Measurement and Evaluation

Notes (7) For meaningfulness of value of t, either of 0.05 or 0.01 meaningful levels are chosen.
If the value of t is meaningful, the statement is accepted as a statement of
discriminating power. If the value of n is large, that is more than 30, then it can be
taken as meaningful at 0.05 level on its value being more than 1.65, and at 0.01 on it
being more than 2.33. If the value of n is small, it would need to refer to the t values
table for seeing its meaningfulness. In the following table number—4, the values of
t have been shown for its meaningfulness at .05 and .01 levels. The value of degree
of freedom is known by the following formula for comparison of two groups :
d = n + n – 2
f H L
In which, d = Degree of freedom
f
n = Number of people in the top group
H
n = Number of people in the bottom group
L
Table
t-Values for One tailed Test
dt .05 .01

10 1.81 2.76
20 1.72 2.53
30 1.70 2.46
40 1.68 2.48
50 1.68 2.40
60 1.67 2.39
70 1.67 2.38
80 1.66 2.38
90 1.66 2.37
100 1.66 2.36
200 1.65 2.35
300 1.65 2.34
400 1.65 2.34
more than 500 1.65 2.33

(8) On the basis of meaningful value of t, 30-40 statements are selected. Care is taken in
selection of statements to see that some of the statements are positive and some of
them negative.
(9) The selected statements are arranged in a random order to prepare the attitude
scale.
(10) Having prepared the attitude scale, the reliability and validity of the scale is found
out using Test-retest method or Split-half method.
(11) Thus prepared attitude scale is administered on those people whose attitude has to
be measured. Their scores on various statements of the scale are obtained according
to the above mentioned marking process. The obtained scores of a person on all
statements will indicate his attitude.
(12) For analysis of obtained scores, they can be changed into t-values or percentiles.
The constructor of the attitude scale can also prepare a conversion table for it.
(iv) Suffir’s Method of Successive Difference : The method of successive difference
developed by Suffir is an improved form of Thurston’s and Chave’s Equal Appearing
Intervals method. Its scale statements need the decisions of only one person. So, when
the number of statements is large, this method is appropriate. In this method, the

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