A study compares the symptom reduction of two different FDA-approved migraine medications by randomly assigning chronic migraine sufferers to take either Drug A or Drug B for a month. Which design is used?

Between-Participants experiment

A study tests participants' reaction times to visual stimuli, has them drink a high-sugar energy drink, and tests reaction times again 30 minutes later to see if scores improved. Which design is used?

Within-participants experiment

A study surveys adults at age 20, 30, 40, and 50 to track how their political affiliations and voting behaviors shift over the course of their lifespan. Which design is used?

Cross-sectional study

A study investigates whether college students with higher extraversion scores tend to hold a higher number of leadership positions on campus. Which design is used?

Correlational study

A study compares the vocabulary size of three different age groups, toddlers (age 2), preschoolers (age 4), and kindergarteners (age 6), all measured during the month of October. Which design is used?

Cross-sectional study

A researcher takes a job as a barista at a local coffee shop for three months to secretly make coded observations about coping strategies employees use with rude customers.

Personal observational research

A correlation coefficient of r = -0.85 indicates

A strong negative relationship where one variable causes a decrease in the other

In a study testing the effect of a new teaching method on math test scores, the researcher ensures that all students take the exam in the exact same room at the exact same time of day. Time of day and room location are:

Control Variables

What is the defining feature that separates a quasi-experiment from a true experiment?

The use of random assignment to conditions

To avoid order effects in a within-subjects design, a researcher ensures that half the participants complete Task A then Task B, while the other half complete Task B then Task A. This is known as:

Counterbalancing

Which of the following is the best example of an attention check in an online survey?

Including the item: 'Please select Strongly Disagree for this question to demonstrate you are reading carefully.'

Under what conditions is it scientifically and ethically acceptable to exclude outlier data from your reported results?

Only when exclusion criteria are clearly stated, justified, and ideally pre-registered ahead of time

A new self-report measure of 'financial impulsivity' accurately predicts how much credit card debt participants accumulate over the next five years. This measure demonstrates excellent:

Criterion Validity

If a digital scale gives you a wildly different weight reading every time you step on it within a five-minute window, the scale has:

Poor reliability (and therefore poor validity)

If an experimental study features a 2 x 4 x 2 factorial design, how many total unique experimental conditions are in the study?

16 conditions

Changing an alpha level (α-level) from α = .05 to α = .01 for a hypothesis test would:

Decrease the chance of a Type I error and increase the chance of a Type II error

A researcher asks participants to select their primary language from a list of options (English, Spanish, Mandarin, Other). Which scale of measurement is being used?

Nominal

A researcher records the total number of children a participant has raised. Because a participant cannot have 1.4 or 2.8 children, this variable represents a:

Discrete variable --> measurement in between units

In a 10-year longitudinal study on depression treatments, participants experiencing the most severe symptoms drop out over time, leaving only those with mild symptoms in the final sample. This threat to internal validity is known as:

Attrition --> when people drop out of a study

A researcher stands outside the student campus center at 1:00 PM on a Tuesday and surveys the first 50 students who walk past. This sampling technique is called:

Convenience sampling

Defining the abstract concept of 'anxiety' specifically as a participant's score on a 10-item self-report questionnaire is an example of:

Operationalizing a variable  taking an idea and talking about how you're actually going to manipulate it

A researcher observes a strong positive correlation between the number of firefighters sent to a fire and the total dollar amount of property damage caused. The unmeasured variable of 'fire size' that drives both is a:

Third variable/confound

Two teaching assistants independently grade the same stack of 50 essay exams using a detailed rubric. Afterwards, the professor correlates their assigned scores to ensure consistency. The TAs are establishing:

Inter-rater reliability

Which of the following Pearson correlation coefficients (r) indicates the WEAKEST relationship between two variables?

r= +0.12

A study finds that public speaking significantly increases heart rate, but this effect is much stronger for individuals with social anxiety than for individuals without social anxiety. In this study, 'social anxiety' acts as a:

Moderator (moderating variables)

A study finds that eating dark chocolate improves exam scores, but further analysis reveals that dark chocolate boosts alertness, which in turn leads to better exam scores. In this explanatory model, 'alertness' acts as a:

Mediator (mediating variable)

Dr. Pumpernickel believes that wearing a bright neon green hat makes street fundraisers collect significantly more charity donations. To test this, he stands outside a grocery store wearing the green hat for 15 minutes on Tuesday morning and collects $12. On Wednesday morning, he stands in the same spot for 15 minutes wearing no hat and collects $10. He concludes that wearing a neon hat has no effect on donation behavior. Assuming neon hats actually DO increase donations in the real world, identify the major statistical and methodological flaws with Dr. Pumpernickel's study that led to this failure to find an effect

Same day, only Dr. Pumpernickel wearing the hat, not enough data collected

Explain the 'third-variable problem' and the 'directionality problem' . Why do these two conceptual and statistical challenges prevent researchers

Third variable problem occurs when two variables appear to be related, but the association is actually due to the influence of a third, unmeasured variable that causes both. The directionality problem arises when a correlation exists but its unclear which variable causes the other. Correlational data can show two variables move together, but it cannot prove that one causes the other because of uncontrolled confounding (third variable) and ambiguous temporal order (directionality). A correlation can hint at a possible causal relationship. Correlation alone cannot suggest causation without certainty

Explain the relationship between setting an alpha level, Type 1 error, and Type 2 error. If a clinical researcher lowers their alpha level from a= .05 to a=.001, how does this affect their chances of making a Type 1 vs Type 2 error?

The alpha level is the pre-set probability of committing a Type 1 error, lowering reduces Type 1 error risk but increases Type 2 error risk unless other study factors change. If a clinical researcher lowers their alpha level, Type 1 error drops, leaving fewer false positives. However, Type 2 error increases. This is because rejecting H0 becomes stricter.

Why does maximizing internal validity often come at the expense of external validity? Are certain research designs (e.g., lab experiments vs. naturalistic field studies) inherently higher in one type of validity over the other?

Maximizing internal validity often reduces external validity because the methods that tightly control confounds and isolate causal effects (e.g., lab experiments) can make results less representative of real-world contexts, while designs that enhance generalizability (e.g., field studies) often introduce more controlled variation that threatens causal inference.