S W 313 Chapter Notes - Chapter 12 - pg 244-255: Quasi, Random Assignment, Internal Validity
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This procedure involves providing the test intervention to the comparison group after both groups complete the posttest. Additional threats to the validity of experimental and quasi- External validity the extent to which we can generalize the findings of a study to settings and populations. One major factor that affects external validity is the representativeness of the sample. Problems in external validity abound in the literature that evaluates social work practice and programs. Cross-sectional studies examine a phenomenon by taking a cross section of it at one point in time. Recognizing that simple correlations at one point do not permit causal inferences, researchers using cross-sectional designs may attempt to rule out the plausibility of rival hypotheses by controlling for alternative variables through multivariate statistical procedures. Cross-sectional designs are commonly used in descriptive or exploratory research. Cases may need to be selected using nonprobability sampling.
