A researcher randomly assigns participants to a treatment or control condition in a laboratory. Which type of validity does random assignment most directly strengthen?
AExternal validity
BEcological validity
CInternal validity
DConstruct validity
Random assignment eliminates systematic differences between groups at baseline, making it far more likely that any observed outcome differences are caused by the treatment rather than confounding variables. This directly strengthens internal validity — the confidence that the study measured a genuine causal relationship. External validity (generalizability) is a separate concern and may actually be weakened by artificial laboratory conditions.
Question 2 True / False
Exploratory research designs lack scientific rigor because they do not begin with a formal hypothesis.
TTrue
FFalse
Answer: False
Exploratory research is rigorous by design — it is the appropriate strategy when a phenomenon is poorly understood and the goal is to generate, not test, hypotheses. Rigor in exploratory research comes from systematic data collection, transparent methods, and careful interpretation. Hypothesis-testing is one form of scientific rigor, not the only one.
Question 3 Short Answer
What is the fundamental tension between internal and external validity, and how do researchers typically manage it?
Think about your answer, then reveal below.
Model answer: Internal validity (accurately measuring a causal relationship) and external validity (findings generalizing to real-world settings) often trade off: tight experimental control strengthens internal validity but reduces ecological realism. Researchers manage this tension by replicating findings across varied settings, using quasi-experimental or mixed-methods designs, or explicitly scoping claims to match the study context.
A perfectly controlled laboratory experiment rules out confounds (high internal validity) but may use artificial conditions, convenience samples, or limited settings that do not reflect the real world (low external validity). Recognizing this trade-off — rather than pretending it does not exist — is a mark of sophisticated research design.