Key Terms
Statistics
The science of collecting, analyzing, interpreting, and presenting data. Probability: a mathematical tool for studying r
Descriptive statistics
Organizing and summarizing data (graphs, averages). Inferential statistics: using data from a sample to draw conclusions
Population
The entire group being studied — all individuals, objects, or measurements of interest.
Sample
A subset of the population; what you actually collect data from.
Parameter
A number describing a characteristic of the POPULATION. (Usually unknown; that's why we sample.)
Statistic
A number describing a characteristic of the SAMPLE. (What you calculate; used to estimate the parameter.)
Variable
A characteristic of interest measured for each member of the population. Notated with capital letters (X, Y).
Data
The actual values of the variable. Plural.
Study goal
Find the average time college students study per night.
Two more terms used constantly
Mean: sum of values divided by number of values; often called "average." Proportion: number of successes divided by tota
Numerical (Quantitative)
Values are numbers with equal units; math makes sense.
Example
Data measured to the nearest whole number — report the mean to the nearest tenth.
Categorical (Qualitative)
Values are names or labels; math doesn't apply.
Discrete
Result of COUNTING. Takes on specific whole-number values.
Examples
Temperature in Celsius or Fahrenheit, calendar years.