Chapter 1 Statistics Terms

statistics

the science of collecting, organizing, presenting, analyzing, and interpreting data.

descriptive statistics

methods for organizing, summarizing, and presenting data in an informative way.

inferential statistics

methods used to determine something about a population on the basis of a sample.

population

the entire set of objects or individuals of interest.

parameter

a summary measure for a population ex. the mean

statistic

a summary measure for a sample ex. the mean used as estimate for a population parameter

sample

a portion or part of the population of interest.

qualitative variables

a categorical variable, or an "attribute" ex. color of your hair, gender, race, what state you live in. things can be put into categories. (nominal and ordinal level data)

quantitative variables

variables who's value can be counted or measured ex. the number of students in a classroom, the outdoor temperature, the amount of gas in your car. (discrete or continuous?) (interval and ratio-level data)

discrete variables (quantitative)

quantitative variables that can assume only certain values and there are usually gaps between those values, also referred to as counts data. ex. the number of finance majors, the number of courses you are registered for.

continuous variables (quantitative)

quantitative variables that can assume any value within a given interval. Typically measured variables. ex. temperature in the room, speed of a car.

nominal level data (qualitative)

data variables that can only be categorized and counted. (lowest) ex. the state that you live in

ordinal level data (qualitative)

data that can be placed into categories and then the categories can be ordered. The orders may be according to the "best", "largest", or "most popular" for example. (low) ex. year in college (rankings are also in this category)

interval level data (quantitative)

measure that includes all the properties of ordinal data, but in addition, the difference between successive categories is consistent. (high) ex. temperature (only rises one degree at a time), shoe size (rises by half measurements)

ratio-level data (quantitative)

measure that includes all properties of interval data, but in addition, the 0 point is meaningful and therefore meaningful ratios can be formed. (highest) ex. the number of gallons of gas in your car (can be zero), the speed a car is traveling (can be zero)