Introduction to Biostatistics: Sample Size and Randomization

This set of vocabulary flashcards covers essential concepts of sample size determination, sampling methods, and randomization techniques in biostatistics.

$$n$$

The symbol used to represent sample size, which is the number of individuals studied.

Random error

A type of error that is reduced when larger sample sizes are used in research.

Sample size factors

Variables that influence the required number of participants, including margin of error, variability, effect size, and confidence levels.

Statistical Power

The ability to detect true differences in a study, which commonly equals $80\%$ and depends on sample size.

Type II Error

A statistical error that is reduced by having higher statistical power.

Probability Sampling

A sampling method that uses chance to select study participants to reduce bias and improve representativeness.

Systematic sampling

A probability sampling method that selects participants using specific intervals.

Stratified sampling

A probability sampling method that selects participants from defined subgroups.

Cluster sampling

A probability sampling method that selects participants in groups.

Non-probability sampling

Sampling methods such as convenience, purposive, and snowball sampling that do not use chance and may introduce bias.

Convenience sampling

An easy non-probability sampling method that may negatively affect the representativeness of the study.

Purposive sampling

A non-probability sampling method where specific individuals are selected for a study.

Snowball sampling

A non-probability sampling method used to recruit participants through other participants.

Randomization

The process of assigning participants to groups by chance to reduce confounding and improve comparability.

Simple randomization

A randomization type that uses equal probabilities for assigning participants to groups.

Block randomization

A randomization type used to ensure that group sizes are balanced.

Stratified randomization

A randomization type used to balance specific participant characteristics across groups.

Randomized Controlled Trials (RCTs)

A research design that used randomization to improve validity, but can be limited by high costs, ethical concerns, or limited generalizability.