SM

Measuring Variables

Definition (#f7aeae)

Important (#edcae9)

Extra (#fffe9d)

Measuring behavior:

Behaviour can be measured in many ways, a common measurement is to ask people how they feel.

Validity:

  • Refers to truth or accuracy and is supported by available evidence.

  • Construct Validity: Whether the measure that is used actually measures the construct it is intended to measure.

  • The validity of a psychological tool is determined by whether it measure this construct.

Indicators of Construct Validity:

  1. Face Validity: Involves only judgment of whether the content of the measure appears to actually measure the variable.

  2. Content Validity: Comparing the content of the measure with content that defines the construct.

  3. Concurrent Validity: To examines the relationship between the measure and a criterion behaviour at the same time.

  4. Convergent Validity: Examines the extent to which scores on the measure are related to scores on other measures of the same/similar construct.

  5. Discriminant Validity: Opposing constructs should have an opposite relationship, discriminate between construct being measured and unrelated constructs.

Others:

  1. Internal validity:

    • Ability to draw conclusions about the causal relationship from the results of a study.

    • A study has high internal validity when strong inferences can be made that one variable caused changes in the other variable .

    • Analysis of 3 elements:

      1. Temporal Precedence: IV before DV.

      2. Covariation: Both groups sharing condition; DV systematically changes as IV changes.

      3. Eliminate plausible alternatives: The difference is attributable to the IV.

  2. External Validity:

    • Extent to which the results can be generalized to other broader contexts.

    • 2 types:

      1. Population validity: How well the results generalize to the wider population.

      2. Ecological validity: How well the results generalize to real life settings.

Reliability:

  • The consistency or stability of a measure of behaviour.

  • True score: A true value on a real scale.

  • Measurement error: Difference between a true score and a measured score is measurement error.

  • A reliable measure of intelligence will yield similar results each time the individual is measured.

Measuring Reliability:

  • Pearson-Product Moment Correlation Coefficient: This Correlation Coefficient (r) can range from 0.00 to (+/-) 1.00.

  • Correlation of 0.00 tells us that the 2 variables are not related at all; lower reliability. The closer a correlation is to 1.00, the stronger is the relationship; higher reliability.