SULEYMAN DEMIREL UNIVERSITY презентация, доклад

Слайд 1SULEYMAN DEMIREL UNIVERSITY
FACULTY of EDUCATION and HUMANITIES

ASSESSMENT
Lecture 3: RELIABILITY (Part

I)

Reliability coefficient
Standard errors of measurement

SULEYMAN DEMIREL UNIVERSITYFACULTY of EDUCATION and HUMANITIESASSESSMENTLecture 3: RELIABILITY (Part I) Reliability coefficient Standard errors

Слайд 2Reliability
A test is reliable if it is consistent within itself

and across time.

Слайд 3Let’s compare two tests in Table 1 and Table 2

Слайд 4TABLE 1 SCORES ON TEST A

Слайд 5TABLE 2 SCORES ON TEST B

Слайд 6The reliability coefficient

A reliability coefficient might be used to quantify

the reliability of a test.

The ideal reliability coefficient is

1.

The reliability coefficientA reliability coefficient might be used to quantify the reliability of a test. The ideal

Слайд 7The reliability coefficient

Lado (1961)

Слайд 8How to calculate the reliability coefficient

There are two types of

methods:
test-retest

split half

Слайд 9For example, let us take the following sets of scores:

Слайд 10Calculating the correlation coefficient on a calculator for the above

half scores

Press the key to engage the calculator’s statistical functions.
Tap

in 55.
Press one of the entry keys (the calculation manual will tell you which).
Tap in 59.
Press the other entry key.
Repeat 2 to 5 for the other pairs of scores.
Press the key for Correlation coefficient (probably marked ‘r’)

Calculating the correlation coefficient on a calculator for the above half scoresPress the key to engage the

Слайд 11By means of a simple formula (the Spearman-Brown formula) it

is possible to estimate the reliability of the whole test.

By means of a simple formula (the Spearman-Brown formula) it is possible to estimate the reliability of

Слайд 12Estimating reliability of full test from coefficient based on split

halves

The formula to use is:

Reliability of whole test = 2

x coefficient for split halves
1 + coefficient for split halves

In the present case: 2 x 0.95
1 + 0.95

= 1.90
1.95

= 0.97
Using the formula, we obtain a figure of 0.97, which indicates very high reliability.

Estimating reliability of full test from coefficient based on split halvesThe formula to use is:Reliability of whole

Слайд 13Scorer reliability

Multiple choice test the scorer reliability coefficient would be

1.

The test, carried out by a computer, is said

to be objective.

Subjective tests will not have reliability coefficients of 1

However, it is possible to obtain scorer reliability coefficient of over 0.90 for the scoring of compositions.

If the scoring of the test is not reliable, the test results cannot be reliable either.