UNIT 1 STATISTICS VOCAB REVIEW

Census

A survey conducted by including every element of the population.

Cluster

A subgroup (usually geographical) of the population that is representative of the population.

Cluster sampling

A sampling technique in which the population is divided into clusters and a sample is chosen from one or a few clusters.

Continuous variable

A (quantitative) variable that can assume any numerical value over a certain interval or intervals.

Control group

The group on which no condition is imposed.

Convenience sample

A sample that includes the most accessible members of the population.

Cross-section data

Data collected on different elements at the same point in time or for the same period of time.

Data or data set

Collection of observations or measurements on a variable.

Descriptive statistics

Collection of methods for organizing displaying and describing data using tables, graphs, and summary measures.

Designed experiment

A study in which the experimenter controls the assignment of elements to different treatment groups.

Discrete variable

A (quantitative) variable whose values are countable.

Double-blind experiment

An experiment in which neither the doctors (or researchers) nor the patients (or members) know to which group a patient (or member) belongs.

Element/Member

A specific subject or object included in a sample or population.

Experiment

A method of collecting data by controlling some or all factors.

Inferential statistics

Collection of methods that help make decisions about a population based on sample results.

Judgement sample

A sample that includes the elements of the population selected based on the judgement and prior knowledge of an expert.

Nonresponse error

The error that occurs because many of the people included in the sample do not respond.

Nonsampling errors/Bias

The errors that occur in the collection, recording, and tabulation of data.

Observation/Measurement

The value of a variable for an element.

Observational study

A study in which the assignment of elements to different treatments is voluntary, and the researcher simply observes the results of the study.

Population/Target population

The collection of all elements whose characteristics are being studied.

Qualitative/Categorical variable

A variable that cannot assume numerical values but is classified into two or more categories.

Quantitative variable

A variable that can be measured numerically.

Quota sample

A sample selected in such a way that each group or subpopulation is represented in the sample in exactly the same proportion as in the target population.

Random sample

A sample drawn in such a way that each element of the population has some chance of being included in the sample.

Randomization

The procedure in which the elements are assigned to different (treatment and control) groups at random.

Representative sample

A sample that contains the characteristics of the population as closely as possible.

Response error

The error that occurs because people included in the survey do not provide correct answers.

Sample

A portion of the population of interest.

Sampling frame

The list of elements of the target population that is used to select a sample.

Sampling/Chance error

The difference between the result obtained from a sample survey and the result that would be obtained from the census.

Selection error

The error that occurs because the sampling frame is not representative of the population.

Simple random sampling

When all samples of the same size selected from a population have the same chance of being selected.

Statistics

Science of collecting, analyzing, presenting, and interpreting data and making decisions.

Stratified random sampling

A sampling technique in which the population is divided into different strata and a sample is chosen from each stratum.

Stratum

A subgroup of the population whose members are identical with regard to the possession of a characteristic.

Survey

Collecting data from the elements of a population or sample.

Systematic random sampling

A sampling method used to choose a sample by selecting every k-th unit from the list.

Target population

The collection of all subjects of interest.

Time-series data

Data that give the values of the same variable for the same element at different points in time or for different periods of time.

Treatment

A condition (or set of conditions) that is imposed on a group of elements by the experimenter. This group is called the treatment group!

Variable

A characteristic under study or investigation that assumes different values for different elements.

Voluntary response error

The error that occurs because a survey is not conducted on a randomly selected sample, but people are invited to respond voluntarily to the survey.