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Collecting Data flashcards

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What does “Simple Random Samples” mean?Sampling Methods
A design with equal selection probability for every subset of the specified size.
What important condition applies to simple random samples?Sampling Methods
Equal individual inclusion probabilities alone do not establish a simple random sample.
What does “Systematic Sampling” mean?Sampling Methods
A sample selected at regular list intervals after a random start.
What important condition applies to systematic sampling?Sampling Methods
Periodicity in list order can bias a systematic sample.
What does “Stratified Sampling” mean?Sampling Methods
A design that samples separately within defined population subgroups.
What important condition applies to stratified sampling?Sampling Methods
Sampling within every stratum is different from selecting only some clusters.
What does “Nonresponse Bias” mean?Bias
Distortion arising when responding units differ from missing invited units.
What important condition applies to nonresponse bias?Bias
A high response rate does not guarantee absence of nonresponse bias.
What does “Undercoverage” mean?Bias
Exclusion of target-population units from the sampling frame.
What important condition applies to undercoverage?Bias
Larger samples cannot by themselves repair an incomplete sampling frame.
What does “Observational Comparisons” mean?Observational Studies Versus Experiments
A comparison of measured groups without randomized exposure allocation.
What important condition applies to observational comparisons?Observational Studies Versus Experiments
Association alone does not establish causation.
What does “Random Assignment” mean?Observational Studies Versus Experiments
Chance-based allocation of experimental units to treatment conditions.
What important condition applies to random assignment?Observational Studies Versus Experiments
Random assignment and random sampling serve different purposes.