Stats Chap 1

Census

A process by which every member of a population is studied.

Sample survey

A method of data collection where a part of the population is examined to infer about the whole population.

Experiment

An investigation where treatments are applied to units to observe their effects on outcomes.

Observational study

A study where no treatments are assigned, and conditions are naturally occurring.

Sampling Frame

The list of all members of a population from which the sample is taken.

Random Sample

Each member of the population is equally likely to be included in the sample.

Simple Random Sample (SRS)

A sample chosen so that every possible sample of a given size has an equal chance of being selected.

Systematic Sample

A sample in which members are chosen according to a specified pattern.

Stratified Random Sample

A sample where subgroups in the population are represented proportionately in the sample.

Cluster Sample

A sample where the population is divided into clusters, and entire clusters are randomly selected.

Sampling Bias

When the technique used to obtain the sample results in a sample that does not represent the population.

Undercoverage

Occurs when some parts of the population are systematically excluded from the sampling.

Non-Response Bias

Bias that can occur when respondents choose not to respond to a survey.

Response Bias

Bias resulting from respondents not providing truthful or accurate answers.

Placebo

A dummy treatment that is used to isolate the genuine effect of a treatment in an experiment.

Single-blind

An experimental design in which the participants do not know whether they are receiving the treatment or a placebo.

Double-blind

An experimental design in which neither the participants nor the experimenters know who is receiving the treatment or placebo.

Completely Randomized Design

An experimental design where subjects are randomly assigned to treatment and control groups.

Matched Pair Design

An experimental design where experimental units are paired based on a shared characteristic.

Block Design

An experimental design where subjects are grouped into similar units, then treatments are randomly assigned within each block.

Nominal level of measurement

A variable level where values are used to name or categorize without implying any order.

Ordinal level of measurement

A variable level that allows for values to be ordered or ranked.

Interval level of measurement

A variable level where differences between values have meaning, but zero does not mean absence.

Ratio level of measurement

A variable level that allows for meaningful ratios and where a value of zero indicates absence of quantity.