Experimental Design Flashcards
7 cards from real AP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Experimental Design flashcards as text
An experiment uses a matched pairs design where each participant is tested under both the old and new software interfaces on different days. The order of interfaces is randomized for each participant. What does randomizing the order control for?
Answer: Carryover or order effects
Randomizing order in a matched pairs design controls for carryover and order effects that could bias results.
A clinical trial randomly assigns 500 patients to drug A and 500 to a placebo. After the trial, it is discovered that patients in the drug A group were, on average, younger. This is an example of:
Answer: Chance imbalance due to random variation
Random assignment does not guarantee perfect balance — chance variation can create group differences, especially with smaller samples.
Which of the following best describes the principle of replication in experimental design?
Answer: Using enough experimental units per treatment to detect real effects
Replication means having multiple experimental units per treatment group so that results are reliable and not due to a single unusual unit.
A study compares two teaching methods by having Teacher A use Method 1 and Teacher B use Method 2. The teaching method is confounded with:
Answer: The teacher (a potential lurking variable)
Because each teacher uses only one method, any observed difference could be due to the teaching method or the individual teacher.
In an experiment testing three doses of a medication, a researcher uses a Latin square design to control for both time period and patient order effects. This is an extension of:
Answer: Blocking in two directions simultaneously
A Latin square design blocks in two directions (rows and columns) simultaneously, controlling for two sources of variation.
A researcher claims that drinking coffee causes increased productivity because a survey shows coffee drinkers are more productive. The major flaw in this causal claim is:
Answer: The study is observational and cannot establish causation
A survey is observational — without random assignment to treatments, causal claims cannot be supported.
When comparing a new exercise program to a control group, a researcher finds that both groups improve over time. The improvement in the control group is most likely due to:
Answer: Regression to the mean and natural improvement over time
Control groups often show improvement due to natural changes over time, regression to the mean, and general health awareness effects.