Population, Samples, and Research Reports Flashcards

Vocabulary flashcards covering population and sampling concepts, research report sections, APA formatting, and t-test statistics.

Sample

A smaller group or subset of a population that is actually studied and used to generalize findings to the larger population.

Parameters

The numbers that describe a whole population, such as the mean weights of all cats in Greece.

Statistics

Values derived from a sample, like the sample mean, used to estimate the true parameter of the population.

Representative Sample

A sample that accurately reflects the characteristics of the whole population to provide a good estimate.

Opportunity Samples

People who are easy to access for recruitment; they are quick and convenient but not truly random.

Sampling Distribution

A model showing what averages from many similar samples would look like if we repeated the sampling process many times.

Central Limit Theorem

The principle that the sampling distribution is always normally distributed if the sample size is $\geq 30$, even if the population distribution is not.

Z-score

A value that expresses data in terms of its standard deviation to make different normal distributions comparable, resulting in a mean of zero.

Abstract

A short overall summary of research, usually $100-250$ words, covering background, methods, findings, and meaning.

Literature Review

A section of the introduction that describes and critiques previous relevant research to show why the current research is necessary.

Et al.

A citation convention used in-text when a work has three or more authors, following only the first author's surname.

Apparatus

Equipment used in an experiment such as computers, eye trackers, or heart rate monitors.

Materials

Items used in a study such as questionnaires or vignettes.

Independent Variable (IV)

The variable in an experiment that is manipulated or observed to see its effect on the outcome.

Dependent Variable (DV)

The outcome that is measured in an experiment to see if it is influenced by the independent variable.

Procedure

The chronological order of how a study took place from the perspective of the participant, including consent, trials, and debriefing.

Descriptive Statistics

Statistics used to describe data (e.g., mean, median, and standard deviation) rather than to test hypotheses.

Inferential Statistics

Statistics used to decide whether observed differences are likely to be real or simply due to sampling variability (e.g., p-values).

Parametric Tests

Statistical tests that assume data follows a particular (normal) distribution and use population parameters like mean and variance.

Non-parametric Tests

Tests that are robust to skew and outliers, make fewer assumptions about distribution, and often use ranks instead of raw scores.

T-test

A statistical test used to determine if there is a significant difference between the means of two groups or between a mean and a known value.

T-statistic

A calculated number that summarizes how big the difference between groups is relative to the noise or natural variability in the data.

P-value

The probability of getting a result by chance; a result is typically called significant if $p < 0.05$.

Degrees of Freedom (df)

A value linked to sample size representing how many data points were truly free to vary before the final calculation.

Cohen's d

A measure of effect size that indicates the magnitude of the difference between groups, independent of sample size and units.