Inferential statistics notes

Descriptive statistics

Methods that summarize and describe the raw data collected by researchers.

Inferential statistics

Use sample data to draw conclusions or make inferences about the target population.

Probability

Assessment of the likelihood that results are due to chance variation; significant results are those with a probability of 0.05 or less.

Null hypothesis

The hypothesis that there is no effect or no difference, which is tested against the alternative hypothesis.

Alternative hypothesis

The hypothesis that posits a significant effect or difference, opposing the null hypothesis.

Statistical tests

Tools used to determine if the results of a study are statistically significant.

Degrees of freedom (df)

A statistical concept used to determine the number of independent values in a calculation; calculated as (r-1)x(c-1).

Sign test

A non-parametric test used to determine if there is a difference between two related samples.

Chi-squared test

A statistical test used to determine if there is a significant association between categorical variables.

Mann Whitney test

A non-parametric test used to compare differences between two independent groups.

Wilcoxon test

A non-parametric test used to compare two related samples.

Spearman’s rho

A non-parametric measure of rank correlation that assesses how well the relationship between two variables can be described.

Critical value

The threshold in a statistical test beyond which the null hypothesis is rejected.

One-tailed test

A hypothesis test that determines whether a parameter is greater than or less than a certain value.

Two-tailed test

A hypothesis test that determines whether a parameter is significantly different from a certain value in either direction.

Levels of data - Nominal

Data that can only be categorized (e.g., city of birth, marital status).

Levels of data - Ordinal

Data that can be categorized and ranked (e.g., top 5 Olympic medalists, Likert scales).

Levels of data - Interval

Data that can be categorized, ranked, and is evenly spaced (e.g., test scores, temperature).