Key Concepts

• When data is gathered from a sample, we can use statistics, like means and proportions, to summarize the data.
• When data is gathered from a sample that is representative of the population, inferential statistics can be used to make conclusions about the population’s parameters.

Glossary

average (mean): a number that describes the central tendency of the data

categorical variable: variables that take on values that are names or labels

data (singular is datum): a set of observations (a set of possible outcomes). Most data can be put into two groups: qualitative (an attribute whose value is indicated by a label) or quantitative (an attribute whose value is indicated by a number).

dot plot: a number line and dots (or points) positioned above the number line

integers: includes the negative natural numbers in the set of whole numbers, e.g. [latex]\{\dots,-3,-2,-1,0,1,2,3,\dots\}[/latex]

irrational numbers: the set of numbers that are not rational, are nonrepeating, and are nonterminating, e.g. [latex]\{h|h\text{ is not a rational number}\}[/latex]

natural numbers: the numbers used for counting, e.g. [latex]\{1,2,3,\dots\}[/latex]

numerical variable: variables that take on values that are indicated by numbers

parameter: a number that is used to represent a population characteristic and that generally cannot be determined easily

population: all individuals, objects, or measurements whose properties are being studied

probability: a number between zero and one, inclusive, that gives the likelihood that a specific event will occur

proportion: the number of successes divided by the total number in the sample

rational numbers: fractions written as [latex]\{\frac{m}{n}|m\text{ and }n\text{ are integers and }n\ne 0\}[/latex]

representative sample: a subset of the population that has the same characteristics as the population

sample: a subset of the population studied

statistic: a numerical characteristic of the sample; a statistic estimates the corresponding population parameter

variable: a characteristic of interest for each person or object in a population

whole numbers: the set of natural numbers plus zero, e.g. [latex]\{0,1,2,3,\dots\}[/latex]