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1.5: Chapter 1 - Key Terms and Symbols

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    Glossary of Key Terms and Symbols

    Key Terms

    Census: when every individual of interest is measured.

    Cluster sampling: The population is divided into groups called clusters. Some clusters are randomly chosen, and all individuals in those clusters are polled.

    Continuous data: takes on any value. Continuous data are usually things you measure.

    Convenience sample: when the researcher picks individuals to be included who are easy for the researcher to collect.

    Discrete: data can only take on particular values, like whole numbers. Discrete data are usually things that can be counted with specific values.

    Experiment: when the investigator changes a variable or imposes a treatment to determine its effect.

    Individual: a person or object that you are interested in finding out information about.

    Interval: data that is ordinal, but you can now subtract one value from another, and that subtraction makes sense. You can do arithmetic on this data, but only addition and subtraction. Examples of this are temperature and time on a clock. The zero value is a marker and not an absence of measurement.

    Nominal: data is just a name or category. There is no order to any data, and since there are no numbers, you cannot do any arithmetic on this level of data. Examples of this are gender, car name, ethnicity, and race.

    Observational study: when the investigator collects data merely by watching or asking questions. He doesn’t change anything.

    Ordinal: data that is nominal, but you can now put the data in order since one value is more or less than another value. You cannot do arithmetic on this data, but you can now put data values in order. Examples of this are grades (A, B, C, D, F), place value in a race (1st place, 2nd place, 3rd place), and size of a drink (small, medium, large). Also, it is not measurable.

    Parameter: a number calculated from the population. Usually denoted with a Greek letter. This number is a fixed, unknown number that you want to find.

    Population: a set of all values of the variable for the entire group of individuals.

    Qualitative or categorical variable: the answer is a word or name that describes a quality of the individual.

    Quantitative or numerical variable: the answer is a number, something that can be counted or measured from the individual.

    Ratio: data that is interval, but you can now divide one value by another, and that ratio makes sense. You can now do all the arithmetic on this data. Examples of this are height, weight, distance, and time. The zero value is an absence of measurement.

    Sample: a subset of the population. It looks just like the population, but contains less data. Also, everybody has the same chance of being picked in the sample.

    Simple random sample (SRS): is a sample of size n that is selected from a population in a way that ensures that every different possible sample of size n has the same chance of being selected. Also, every individual associated with the population has the same chance of being selected.

    Statistic: a number calculated from the sample. Usually denoted with letters from the Latin alphabet, though sometimes there is a Greek letter with a ^ (called a hat) above it. Since you can find samples, it is readily known, though it changes depending on the sample taken. It is used to estimate the parameter value.

    Statistics: the study of how to collect, organize, analyze, and interpret data collected from a group.

    Systematic sampling: where you randomly choose a starting place and then select every Kth individual to measure.

    Variable: the measurement or observation of the individual.

    This page titled 1.5: Chapter 1 - Key Terms and Symbols is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Toros Berberyan, Tracy Nguyen, and Alfie Swan.