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Martinez, Maria Regina J. OrCom 109.2 (TFI)2008-18861 Prof. Rafael Villar

INSTRUMENT VALIDITY AND RELIABILITY

I. Validity A true measure

The ability of measurement procedures to produce empirical data consistent with the theoretical meaning

of the concept to be measured

Four Types of Measurement Validity

1. Face Validity

- Easiest type to achieve and most basic kind

of validity

- A scale is accepted as valid if it looks or

sounds valid to the researcher

- A judgement by the scientific community that

the indicator really measures the construct

- Question answered:

On the face of it, do people believe that the

definition and method of measurement fit?

2. Content Validity

- Captures the entire meaning

- Measures should sample or represent all

ideas or areas in a conceptual space

- Question answered:

Is the full content of a definition represented

in a measure?

- Three steps:

1) Specify the content in a constructs

definition2) Sample from all areas of the definition

3) Develop an indicator that taps all of the

various parts of the definition

3. Criterion Validity

- Agrees with an external source

- Uses some standard or criterion that is

known to indicate a construct accurately

- The validity of an indicator is verified by

comparing it with another measure of the

same construct in which a researcher has

confidence

- Two sub-types:

a. Concurrent

- An indicator must be associated with a

pre-existing behavior just that is to be

judged to be valid

b. Predictive

- An indicator predicts future events that

are logically related to a construct

4. Construct Validity

- Multiple indicators are consistent

- Requires a definition with clearly specified

conceptual boundaries

- Question answered:

If the measurement is valid, do the various

indicators operate in a consistent manner?

- Two sub-types:

a. Convergent

- Alike ones are similar

- Multiple measures of the same

construct hang together or operate in

similar ways

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b. Discriminant (divergent)

- Different ones differ

- Indicators of one construct hang

together or converge, but also diverge

or are negatively associated with

opposing constructs

II. Reliability It is a dependable measure

Response is similar and predictable in different times and conditions

The method of conducting a study or the results from it can be reproduced or replicated by other

researchers

Stability and internal consistency

Four Types of Reliability

1. Inter-Rater or Inter-Observer Reliability

- Assesses the degree to which different

observers give consistent estimates of the

same phenomenon

2. Test-Retest Reliability

- Measures the consistency of a measure from

one time to another

3. Parallel-Forms Reliability

- Considers the consistency of the results of

two tests constructed in the same way from

the same content domain

4. Internal Consistency Reliability

- Calculates the consistency of results across

items within a test

III. Relationship Between Validity and Reliability

Reliability is necessary for and easier to achieve than validity, although not a guarantee that a measure will

be valid

A measure can be reliable but invalid

Usually complementary concepts, but sometimes conflict with each other

Sometimes as validity increases, reliability is more difficult to attain (vice versa)

Reliability is easiest to achieve when measure is precise and observable

*Sources are stated on the

cut-and-paste.

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**Tables and examples will be discussed in class.