Final presentation1-research-1

RESEARCH MEDTHODOLOG

Y

GROUP MEMBERS

Sanaullah MallahShazia MallahSaba Pervez

Muhammad AliZainab Younis

Muhibullah Nahrio

TOPIC

VALIDITY AND RELIABLITY

OBJECTIVES• What is validity and reliability

• How and why we use them as tools

• Methods , types, Factors

• Its importance and both concepts together

AN OVERVIEW OF PRESENTATION AS A WHOLE

AND RELIABILITYby

SHAZIA MALLAH

ITS TYPES AND METHODES AS A TOOLS TO KNOW HOW WE USE

IT AND FACTORS

Major types of validityContent-related evidence of validity

Criterion-related evidence of validity

Construct-related evidence of validity

1

2

3

FACTORS AFFECTING VALIDITY

Major Methods of Reliability TEST-RETEST METHOD

EQUIVALENT-FORMS METHOD

INTERNAL-CONSISTENCY METHODS

1

2

3

FACTORS AFFECTING RELIABILITY

VALIDITY AND RELAIBLITY IMPORTANCE AND VALIDITY AND RELIABILTY TOGETHER

EXAMPLEif your scale is off by 5 pounds, it reads your

weight every day with an excess of 5pounds. The scale consistently reports the same weight every day, but it adds 5pounds to your true weight.

•

EXAMPLE• if your scale is off by 5 lbs, it reads your

weight every day with an excess of 5lbs. The scale is reliable because it consistently reports the same weight every day, but it is not valid because it adds 5lbs to your true weight. It is not a valid measure of your weight.

•

• The consistency of the scores obtained—how consistent they are.

• the consistency of your measurement instrument

• the degree to which an instrument measures the same way each time it is used under the same condition with the same subjects

RELAIBLITY

What do I mean by…?

© A. Taylor Do not duplicate without author’s permission

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• Reliability alone does not mean that you have a good instrument however.

• Imagine the following reliable instrument:

0165Every morning GALTON gets on the scale and every morning it reads 165 lbs.

It seems pretty reliable since GALTON hasn’t gained or lost any weight.

One day an elephant got on GALTYON’s scale and it still read 165 lbs.!How is this scale reliable?It does measure the same way under the same conditions (GALTON’s) – but a lot of other conditions too (the elephant and who knows what else).

RELIABILITY


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What in the world is a measurement instrument?• Any tool that you use to measure with…

• What “instrument” might you use to measure the following items?

1. How heavy the apples are

2. How hot the meat is

3. How much orange juice there is

4. How tall the wall is

a scale

a meat thermometer

a measuring cup

a yardstick


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Can it measure how loud the radio is? how full the

glass is?

how smart the girl is?

The ruler may be reliable (and perhaps even valid) but not in these situations!It is only valid for measuring length.

Reliable but not Valid

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What would the following instruments measure?

The size of someone’s foot

EyesightThe perfect amount of spaghetti!

More on Instruments


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What instrument you choose depends on

several factors• Ease of use – do you know how to use it?

.

• Access – do you have access to the instrument?

• Appropriateness – is it the best tool for what you are measuring?

• Accuracy – how precise do your measurements have to be?

• Cost – how expensive is it to use the instrument or interpret the results?

.

SANAULLAH MALLAH

• Validity refers to how well a test measures what it is purported to measure.

• appropriateness, correctness, meaningfulness, and usefulness of the specific inferences researchers make based on the data they collect.

VALIDITY


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Validity asks if an instrument measures what it is supposed to

how “true” or accurate the measurement is.

What

is

Validity?

EXAMPLE

EXAMPLE

SABA PERVEZ

VALIDITY TYPES AS A TOOLAND ITS FACTORS

Major types of validityContent-related evidence of validity



1

2

3

Major types of validityContent-related evidence of validity1

the content and format of the instrument. How appropriate is the content? How comprehensive? Does it logically get at the intended variable? How adequately does the sample of items or questions

represent the content to be assessed? Is the format appropriate?

Major types of validity Criterion-related evidence of validity 2

the relationship between scores obtained using the instrument and scores obtained using one or more other instruments or

measures

Major types of validityConstruct-related evidence of validity3

The nature of the psychological construct or characteristic being measured by the instrument. How well does a measure of the construct explain differences in the behavior of individuals or their

performance on certain tasks.

FACTORS AFFECTING VALIDITY

1. Test-related factors2. The criterion to which you compare

your instrument may not be well enough established

3. Intervening events4. Reliability

MUHIBULLAH

RELIABILITY METHOEDS AS A TOOL

AND ITS FACTORS

Major Methods of Reliability TEST-RETEST METHOD



1

2

3

Major Methods of ReliabilityTEST-RETEST METHOD1

The test-retest method involves administering the same test twice to the same group after a certain

time interval has elapsed

Major Methods of ReliabilityEQUIVALENT-FORMS METHOD2

When the equivalent-forms method is used, two different but equivalent (also called alternate or parallel ) forms of an instrument are administered to the same group of individuals during the same

time period

Major Methods of ReliabilityINTERNAL-CONSISTENCY METHODS3

Internal consistency reliability is a measure of how well the items on the test measure the same

construct or idea.

FACTORS AFFECTING RELIABILITY

1. Test length2. Test-retest interval3. Variability of scores4. Guessing5. Variation within the test situation

ZAINAB YOUNIS

VALIDITY AND RELAIBLITY IMPORTANCE

IMPORTANCE

Reliability and validity are important concepts in research. The everyday use of these terms

provides a sense of what they mean (For example, your friends are reliable. Your

opinion is valid). In research, their use is a little more complex

IMPORTANCERELIABILITY

TEST-RETEST METHOD



VALIDITY Content-related

evidence of validity



IMPORTANCE

ERRORS OF MEASUREMENT

VALIDITY AND RELIABILTY TOGETHER

Putting Reliability and Validity

TogetherEvery instrument can be evaluated on two dimensions:ReliabilityHow consistent it is given the same conditions

ValidityIf it measures what it is supposed to and how accurate it is

Putting Reliability and

Validity Together

Imagine that I have 3 fish tank thermometers, a blue one, a red one, and a green one.

The blue one always reads the same temperature no matter how hot or cold the water is.

The red one shows a different temperature every time even if I just measured it 5 seconds earlier.

The green one seems to read accurately, warm when the water is warm and cold when the water is cool.


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Is it consistent?Is it measuring what it

is supposed to? Is it reliable? Is it valid?

Blue always reads the same temperature no matter what

Red different temperature every time even if nothing has changed

Green warm when the water is warm and cold when the water is cool

Complete the chart below

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Is it consistent?Is it measuring what it

is supposed to? Is it reliable? Is it valid?

Blue always reads the same temperature no matter what

Red different temperature every time even if nothing has changed

Green warm when the water is warm and cold when the water is cool

Yes

No

Yes, the thermometer only changes if the temperature changes

No

No

Yes

Reliable but Not valid

Not reliable Not valid

Reliable and Valid

Complete the chart below

Final presentation1-research-1

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