AP Stat: Chapter 12: Warm Ups 5 and 6

Positive correlation between sales of beer and sales of ice cream. Seasons when sales of beer were above average, sales of ice cream were also above average. Which of the following could be a valid conclusion from these facts?

It is likely that sales of both beer and ice cream are confounded with a lurking variable, sic as seasonal variation in temperature

Block designs are the same as _____ designs

stratified

A stratified random sample addresses the same issues as which of the following experimental designs? A. a block design B. a double blind experiment C. an experiment with a placebo D. a matched pairs design E. a confounded, nonrandomized study

A. a block design

The most important advantage of experiments over observational studies is that A. experiments are usually easier to carry out B. experiments can give better evidence of causation C. confounding cannot happen in experiments D. an observational study cannot have a response variable E. observational studies cannot use random samples

B. experiments can give better evidence of causation

Which of the following is NOT a major principle of good design for all experiments? A. comparison to a control B. replication C. blocking D. randomization E. all of these are important principles for every experiment

C. blocking

In an experiment, an observed effect so large that it would rarely occur by chance is called A. an outlier B. influential C. statistically significant D. bias E. replication

C. statistically significant

If changes in a response variable are due to the effects of the explanatory variable as well as the effects of lurking variables, and we cannot distinguish between these effects, we are said to have A. a cause and effect relation between the explanatory and response variable B. a placebo effect C. confounding D. correlation E. extrapolated

C. confounding

The essential difference between an experiment and an observational study is that A. observational studies may have confounded variables, but experiments never do B. in an experiment, people must give their informed con set before being allowed to participate C. observational studies are always biased D. observational studies cannot have response variables E. an experiment imposes treatments on the subjects, but an observational study does not

E. an experiment imposes treatments on the subjects, but an observational study does not

If there is NO treatment, it is likely to be a ______

observational study