MCAT psych soc research design and bias study guide

What is a cross-sectional study?

A study that analyzes data from a population at a specific point in time. - Snapshot of data - Identifies relationships but not causation.

True or False: Longitudinal studies are conducted over a short time period.

False. Longitudinal studies observe subjects over an extended period, allowing for the examination of changes over time.

Fill in the blank: The __________ variable is manipulated in an experiment.

Independent variable.

What is the purpose of random assignment?

To ensure each participant has an equal chance of being assigned to any group, reducing selection bias.

Compare experimental and observational studies.

Experimental studies manipulate variables to determine cause-effect; observational studies only observe without manipulation.

What type of study uses surveys to gather data?

Descriptive study. - Gathers data on characteristics - Often used for correlational analysis.

Cause → Effect: What is the effect of a placebo?

It can lead to perceived improvements in condition due to belief in treatment, illustrating the placebo effect.

What is the difference between qualitative and quantitative research?

Qualitative research collects non-numerical data (interviews, observations); quantitative research uses numerical data (statistics, surveys).

What is an operational definition?

A clear, precise description of variables and procedures in a study, allowing for replicability.

True or False: Case studies provide broad generalizations about populations.

False. Case studies focus on in-depth analysis of a single case or small group, limiting generalizability.

What is the main focus of a cohort study?

To follow a group (cohort) over time to see how exposure affects outcomes, often in health research.

Identify the term: A group not exposed to the independent variable.

Control group.

What is a meta-analysis?

A statistical technique that combines results from multiple studies to identify overall trends or effects.

Describe the purpose of a control variable.

To eliminate alternative explanations for the relationship between the independent and dependent variables.

What does the term 'sample bias' refer to?

A situation where the sample does not represent the population, leading to skewed results.

Identify two types of non-experimental research.

Correlational research, observational research.

What is sampling bias?

Sampling bias occurs when the sample is not representative of the population, leading to skewed results.

True or False: Confirmation bias helps validate opposing research.

False. Confirmation bias occurs when researchers favor information that confirms their preexisting beliefs.

Identify the bias: Participants self-select into a study.

Self-selection bias. This can lead to non-representative samples.

What is observer bias?

Observer bias happens when researchers' expectations influence their observations and interpretations of data.

Fill in the blank: __________ bias occurs when the outcome influences the study's design.

Outcome reporting bias.

Compare selection bias and attrition bias.

- Selection bias: non-random sample selection. - Attrition bias: loss of participants affecting results.

What is response bias?

Response bias occurs when participants give inaccurate or dishonest answers due to various pressures or preferences.

True or False: Publication bias can lead to a distorted view of research findings.

True. Only positive results are often published, skewing the overall understanding.

What is the Hawthorne effect?

The Hawthorne effect is when participants alter their behavior because they know they are being observed.

Explain the placebo effect.

The placebo effect occurs when participants experience real changes due to their expectations, not the treatment.

Cause → Effect: Observer expectations → __________.

Changes in data interpretation due to bias.

What is selection bias?

Selection bias arises from non-random selection of participants, impacting the study's validity.

Mean vs. Median: Define each.

Mean: Average of values. Median: Middle value when sorted. - Mean is sensitive to outliers. - Median provides better central tendency with skewed data.

True or False: Standard deviation increases with more data points.

False. Standard deviation measures spread of data; more data points do not inherently increase variability.

What is a p-value?

A p-value indicates the probability of obtaining results at least as extreme as the observed data, assuming the null hypothesis is true. Common threshold: 0.05.

Fill in the blank: The _____ of a sample helps estimate the population parameter.

Mean. - Sample mean is used to infer the population mean.

Correlation vs. Causation: Explain difference.

Correlation: Indicates a relationship between two variables. Causation: Implies one variable directly affects another. - Correlation does not equal causation.

Calculate the mean: 2, 4, 6, 8.

Mean = (2 + 4 + 6 + 8) / 4 = 5.

What does a confidence interval represent?

A confidence interval provides a range of values within which the true population parameter is expected to lie, with a certain level of confidence (commonly 95%).

True or False: Larger sample sizes reduce the margin of error.

True. Larger sample sizes lead to more accurate estimates, thus reducing the margin of error in statistical analysis.