biometrics notes (1)

module three

Statistics

The science of collecting, describing, and interpreting data.

Descriptive Statistics

Branch of statistics that summarizes and presents data, such as sample means, charts, or tables.

Inferential Statistics

Branch of statistics that draws conclusions about a population based on a sample.

Population

The entire group you want to study, e.g., all fish in the Chesapeake Bay.

Sample

A smaller group taken from the population for the study, e.g., fish caught with a net.

Experimental Unit (EU)

The individual item or subject being studied, e.g., one fish.

Variable

A characteristic measured on each experimental unit, e.g., fish’s body length.

Quantitative Variables

Numerical variables that can be measured, e.g., weight in grams.

Discrete Variable

Countable values, e.g., number of eggs in a nest.

Continuous Variable

Measured variables that can take any value within a range, e.g., weight in grams.

Qualitative Variables

Descriptive attributes measured on experimental units, e.g., color or blood type.

Nominal Variable

Categories with no order, e.g., gender.

Ordinal Variable

Categories with a meaningful order, e.g., small, medium, large.

Good Sample

A sample that is random, independent, representative, and not biased.

Bias

Systematic favoring of certain outcomes that skews results.

Survey

A study that observes and records data without altering conditions.

Experiment

A study that controls or manipulates variables to observe outcomes.

Data Point

A single value for one variable on one experimental unit.

Data

A collection of all data points from a sample.

Common Sampling Issues

Problems that can skew results, including bias, independence, and representation.