Methodology Week 5

Objectives Quizzes and assignments review Discuss the methodology design and elements Define validity and its types Define reliability and compare to validity

Quizzes and assignments Quiz 3 was due today Introduction assignment due today Lit review assignment is due next week Proposal assignment graded

Methodology Population: to determine the sample and sample size Instrument: tool used to collect the data Experimental procedure: protocol Data collection: answer the questions “What”: What data will be collected, what variables are involved, etc. Data processing and analysis

Methodology Statistical analysis: T-test, ANOVA, etc. Validity and reliability

Validity Internal validity External validity Internal validity refers to the condition that observed differences on the dependent variable are a direct result of manipulation of the independent variable, not some other variable. External validity External validity refers to the condition that results are generalizable, or applicable, to groups and environments outside of the experimental setting. Can findings be generalized back to the population?

Content Validity This approach measures the degree to which the test items represent the domain or universe of the trait or property being measured. Subjective measure of how appropriate the items seem to a set of reviewers who have some knowledge of the subject matter

Construct Validity A construct is defined as a property that is offered to explain some aspect of human behavior, such as mechanical ability, intelligence, etc First the researcher must develop the definition of a meaningful, useable construct Next, the adequacy of the test used to measure it must be evaluated

Criterion Related Validity The ability to detect the presence or absence of one or more criteria considered to represent traits or constructs of interest

Reliability Consistency in results or measures The degree of stability exhibited when a measurement is repeated under identical conditions Must prove reliability before one can prove validity A lack of reliability may arise from divergences between observers or instruments of measurement or instability of the attribute being measured

Test-retest Examines the consistency of the responses between two tests

Alternate-form reliability Use differently worded forms to measure the same attribute Questions or responses are reworded or their order is changed to produce two items that are similar but not identical

Split-halves Method In the split-halves method, the total number of items is divided into halves, and a correlation taken between the two halves.