Measures of Validity Report 2

8/18/2019 Measures of Validity Report 2

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What can you say about the dots on the dartboard?


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Measures of Validity

Definition of Validity

“Degree to which a test or instrument measures what it purports to

measure” - Thomas & Nelson 1996

“The soundness or appropriateness of a test or instrument in

measuring what it is designed to measure”

- Vincent 19992


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Some Helpful Terms

• Construct

– The trait or characteristic that interests us. We might call it a“target” or “what we want to get at”. We create a test to“coer” this attri!ute.

– Vali"it# a""resses how well an assessment techni$ue%roi"es useul inormation a!out the construct ' target.

• (nternal ali"it#

– (s the e)%erimenter measuring the eect o the in"e%en"entaria!le on the "e%en"ent aria!le*

• +)ternal ali"it#

– Can the results !e generalise" to the wi"er %o%ulation*,


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Important distinction!

The term “validity” is used in two different ways

1. Vali"it# o an assessment or method of collecting

data• The ali"it# o a test or $uestionnaire or

interiew

+)am%le

-ath test

is it coering the right content an" conce%ts*

is it also inluence" !# rea"ing leel or !acgroun"

nowle"ge* /ttitu"e assessment

are the $uestions a%%ro%riate*

"oes it assess "ierent "imensions o attitu"es

0intensit# "irection etc.


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Important distinction!

The term “validity” is used in two different ways

2. Vali"it# o a research study • Was the entire stu"# o high $ualit#

• 3i" it hae high internal an" e)ternal ali"it#

• Vali"it# is also assesse" in a %articular conte)t

– / test ma# !e ali" in some conte)ts an" not in

others

– / $uestionnaire ma# !e useul with some %o%ulations

an" not so useul with other grou%s


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2 Types of validity

"riterion#related validity

2 "onstruct validity


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2 Types of validity

"riterion#related validity

• (t is the e)tent to which %eo%le4s scores are correlate" withother aria!les or criteria that relect the same construct.

$%amples&

• /n (5 test shoul" correlate %ositiel# with school %erormance.

• /n occu%ational a%titu"e test shoul" correlate %ositiel# with

wor %erormance.

2 Types

a. "oncurrent validity

'. (redictive validity


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Types of validity

2 Types of "riterion#related validity

a "oncurrent validity

– orecasting the %resent

– how well "oes a test %re"ict current similar

outcomes

– o! sam%les alternatie tests use" to

"emonstrate concurrent ali"it# ei"ence


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2 Types of "riterion#related validity )cont*

• Concurrent Vali"it# – (ners that the test %ro"uces similar results to a %reiousl# ali"ate"

test

– e.g. The V72ma) test is the criterion measure o aero!ic %ower in athletes

Incremental Treadmill Protocol

with expired gas analysis Multi-Stage Fitness (eep! Test


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' (redictive validity

• When the criterion is something that will ha%%en or !e

assesse" in the uture this is calle" %re"ictie ali"it#.

• $%amples&

– how well "oes a test %re"ict uture outcomes

– S+T )8cholastic /%titu"e Test %re"icting 1st #r ,(+

0ra"e :oint /erage

– ,-$ 0ra"uate ;ecor" +)amination scores an" gra"uate

school %erormance


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"xample o# Predictive Validity

$an per#ormance during test % be used to predict #uture per#ormance

in test ?

AB


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2 Types of validity )cont*

2 "onstruct validity

< The e)tent to which an assessment corres%on"s to other

aria!les as %re"icte" !# some rationale or theor#.

< (ners not onl# that the test is measuring what it is su%%ose" to !ut

also that it is ca%a!le o "etecting what should e)ist theoreticall#

< Thereore relates to h#%othetical or intangi!le constructs


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• 2 "onstruct Validity

• When we as a!out a test4s construct ali"it# we are

taing a !roa" iew o the test.

– 3oes the test a"e$uatel# measure the un"erl#ing

uno!sere" construct*

• Construct ali"it# is !ase" on the accumulation o

nowle"ge a!out the test an" its relationshi% to other tests

an" !ehaiors.


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• 2. Construct Vali"it#

• +)am%les

– ( #ou can correctl# h#%othesi=e that +87> 0+nglish or s%eaers oother languages stu"ents will %erorm "ierentl# on a rea"ing test

than +nglish


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Statistical tools that measure validity

• :earson :ro"uct –-oment correlation

• < to "etermine the correlation the measure o the

strength o the relationshi% !etween two aria!les

use" to com%are in"ii"ual scores

– r

Measures of Validity Report 2

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