Criterion for the Good Test

8/2/2019 Criterion for the Good Test

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CRITERION FOR THE GOOD T

By,Mohamed ThasleemReg No- 1116099


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CRITERION FOR THE GOOD T

There are two criteria to decidewhether the scale selected is good

not.


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Reliability Validity


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Reliability means, ability of a scale to produce

consistent result if repeated measurements are

taken. Reliability means the extent to which the

measurement process is free from random erro

Reliability deals with accuracy and consistency

The scale is said to be reliable, if it yields the saresult when repeated measurements are madeunder the constant conditions.

Example: Attitude towards a product or brand

preference.


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Random error is not a constant error but, itdepends on the person using the measuringinstruments or measuring situation.

A random error leads to inconsistency inmeasurements; when the measurements armade on the same objects or persons.

Example of a random error: Theuse of elastscale to measure a persons height. If two

successive measurements are made, the perwho is measuring would stretch the elastic rto different degree on two successive occasitherefore the height measurement would nebe the same even though the persons heighnot changed.


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Respondents are given identical sets of scat two different points of time under almidentical conditions.

The time interval is between 2 to 5 week

The similarity between 2 measurements determined by correlation coefficient. Hthe value ofcorrelation coefficient, greatthe reliability.


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Disadvantages of Test-Retest Method

The interval between first and second test is

the scale will be less reliable.

It is difficult to convince the original respondto take the test for second time.

Second time answer may be influenced by th

first time answer.

For Ex: Assume that, an opinion about the

hospital service is asked. Two weeks later, if

same question is asked, the reply by respond

will be influenced by what was told the first


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In this method 2 equivalent scales are used to

obtain consistent results. The researcher administer one scale to the

respondent.

2 weeks later another scale, which is equivalentfirst one to the same respondent

Greatest problem of this method is to constructscales that appear to be different but have simileffect. This alternative forms test is similar to th

retest method, except that the test retest methouses the same measuring instrument both the t


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In this method 2 or more measurement of the s

concept is taken at the same time and then comto see they agree with each other.

For Ex: Researcher uses choices from stro

agree to strongly disagree to determine

consumer attitude towards the servicerendered by Big Bazaar.

Suppose the researcher prepares 4

statements scale to measure this:


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1. I enjoy shopping at Big Bazaar.

2. All my needs for my household are satisfied

Shopping in Big Bazaar.3. Service provided to me by Big Bazaar isexcellent.

4. I like the front line salesman regarding theservice rendered.

The degree to which the 4 statements showcorrelation across a sample of respondents ind

the Reliability of the measure. If correlation is h

then reliability will also be high.

M th d t i R li bilit


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Methods to improve Reliability

Increase the number of measurements .

Controls used for conducting the experim

must be good. Example (a) Measuring device must be

accurate. (b) The researcher who adminismust be trained to avoid bias in responde

Items to be measured must be stated cle

.The same set of respondents must beinclined to answer the same question a


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The paradigm ofvalidity focused in the question A

measuring, what we think, we are measuring? Succ

the scale lies in measuring What is intended to bemeasured?

Of the two attributes of scaling, validity is most impo

Validity is arguably the most important crite

for the quality of a test. There are several methods to check the

Validity of the scale used for measurement.


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A sales manager believes that there is a c

relation between job satisfaction for a peand the degree to which a person is an

extrovert and the work performance of h

sales force. Therefore, those who enjoy h

job satisfaction and have extrovert

personalities should exhibit high perform

If they do not, then we can question the

Construct Validity of the measure.


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Also Known as Face Validity.

A researcher should define the problemclearely.

Identify the item to be measured.

Evolve a suitable scale for thispurpose.

Exaample for Content Validity:


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Exaample for Content Validity:

An example can be the introduction of new packaged f

When new packaged food is introduced, the product

representing a major change in taste. Thousands of

consumers may be asked to taste the new packaged foo

Overwhelmingly, people may say that they liked the ne

flavor. With such a favourable reaction, the product wh

introduced on a commercial scale may still meet with fa

So, what is wrong? Perhaps a crucial question that was

omitted. The people may be asked if liked the new packfood, to which the majority might have yes but the sa

respondents were not asked, Are you willing to give up

product which you are consuming currently?. In this caproblem was not clearly identified and the item to bmeasured was left out.


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This pertains to how best a researcher can

guess the future performance from the knowledge

Of attitude score?

Example: An opinion questionnaire, which is thbasis for forecasting the demand for a product predictive validity. The procedure for predictivevalidity is to first measure the attitude and thepredict the future behavior. Finally, this followethe measurement of future behavior at anappropriate time. Compare the two results (Pasfuture). If the two scores are closely associated,the scale is said to have predictive validity.

Relationship between Reliability and Valid


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Relationship between Reliability and Valid

If a scale is to Valid, it must be Reliable.

The scale does not have to be valid to

be reliable. Reliability is a necessary but not a

sufficient conditions for Validity. This is

because Validity requires other factors

to be satisfied.

Validity is not a necessary condition forReliability.


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Criterion for the Good Test

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