Internal and External Validity

Internal Validity

• extent to which you can be confident that a cause-and-effect relationship established in a study cannot be explained by other factors.

• controlling as many options / variables to address our experiment.

history, maturation, testing, instrumentation, selection bias, Regression to the mean, Interaction effects, Attrition and Mortality

threats to internal validity

History

unrelated event influences outcomes.

Maturation

outcomes of the study vary as a natural result of time

Instrumentation

threat due to appropriateness and the accuracy of the instrument used and the manner it was used in a study

Testing

a threat to internal validity when a pretest influences the way subjects respond on a posttest

Selection Bias

groups are not comparable at the beginning of the study.

Regression to the mean

occurs when you have a non-random sample from a population and to measure (?) that are imperfectly Correlated.

Interaction Effects

participants from diff. groups may compare notes and either figure out the aim of the study or feel resentful of others.

Attrition and Mortality

occurs when participants choose not to complete a study

Attrition

haharapin / sumuko

Mortality

death

EXTERNAL VALIDITY

Extent to which you can generalize the findings of a study to other measures, settings, or group

Population validity, Demographic validity, Ecological validity

Threats: External Validity

Population Validity

-the extent to which results observed study will generalize to the population from which a sample was selected

-hanggang saan yung scope or core.

Demographic Validity

-specific targets only

-This focuses on whether the results can be generalized across different demographic groups (such as age, gender, income, or education level). ex. STEM students only

ecological validity

-The extent to which a study is realistic or representative of real life.

-Not naturally occurring

1.)Blinding

2) Having control group

3) Equalizing variables

4) Random Selection.

5) Random Assignment / Randomization

6) Use the most appropriate / best measuring equipment

7.) Large sample frame & Sample Size

8.)Accurate simulation of the experiment to the natural setting

9) Replication

Ways to counter THREATS to validity