5. Planning Samples and Experiments Free Online FlashCards

What is a population in statistical research?

The population is the complete group about which a conclusion is intended.

What is a sampling frame?

A sampling frame is the list or procedure used to identify members of the population for possible selection.

What defines a simple random sample?

In a simple random sample, every possible sample of the chosen size has an equal chance of being selected.

How does stratified random sampling work?

Stratified random sampling divides the population into meaningful, nonoverlapping strata, then randomly samples from each stratum.

What happens in cluster sampling?

Cluster sampling randomly selects natural groups and studies every member of selected clusters or samples members within them.

How is systematic sampling performed?

Systematic sampling selects every kth case from an ordered list, usually after choosing a random starting point.

What is the purpose of random selection?

Random selection determines who enters a sample and supports generalizing from that sample to the population.

What is the purpose of random assignment?

Random assignment uses chance to place participants into treatment groups, helping create comparable groups and support cause-and-effect conclusions.

What is bias in a statistical study?

Bias is a systematic tendency for a study's method to produce results that differ from the truth. Increasing sample size generally does not remove flawed design.

What is an observational study?

An observational study measures variables without assigning treatments or deliberately changing the explanatory variable. It can show association but usually cannot establish causation.

What distinguishes an experiment?

An experiment imposes one or more treatments, manipulates an explanatory variable, and measures responses. Random assignment can support cause-and-effect conclusions.

What is a confounding variable?

A confounding variable has effects that cannot be separated from the explanatory variable's effects, threatening a causal interpretation.