AP Stats Chapter 4

voluntary response bias

bias introduced to a sample when individuals can choose on their own whether to participate in the sample

nonresponse bias

bias introduced when a large fraction of those sampled fails to respond

The principle reason for the use of random assignment in designing experiments is that it

creates approximately equal groups for comparison.

The principle reason for the use of controls in designing experiments is that it

distinguishes a treatment effect from the effects of confounding variables.

response bias

leading questions, social desirability

undercoverage

occurs when some groups in the population are left out of the process of choosing the sample

Three factors of good experimental design

randomness, comparison, replication

The reason that blocking (as in a randomized block design) is sometimes used in experimentation is to

reduce variability arising from random assignment.

The principle reason for replication in designing experiments is that it

reduces sampling variability.

random allocation

to eliminate bias in the sampling process

comparison

to reduce the effect of lurking variables

blocking

to reduce variability between subjects in an experimental design

stratified random sampling does for the sampling process what

blocking does for the experimental design