Chapter 1
Chapter Notes

STATISTICS The science of collecting, organizing, presenting, analyzing, and interpreting data to assist in making more effective decisions.

Types of Statistics
DESCRIPTIVE STATISTICS   Methods of organizing, summarizing, and presenting data in an informative way.

INFERENTIAL STATISTICS The methods used to estimate a property of a population on the basis of a sample.

Our main concern regarding inferential statistics is finding something about a population from a sample taken from that population.

POPULATION The entire set of individuals or objects of interest or the measurements obtained from all individuals or objects of interest.

SAMPLE A portion, or part, of the population of interest.
Types of Variables
There are two basic types of variables: (1) qualitative and (2) quantitative
When the characteristic being studied is categorical or nonnumeric, it is called a qualitative variable or an attribute.

Qualitative: Brand of PC; Marital status; Hair color

When the variable studied indicates how many or how much it is called a quantitative variable.

Discrete - Children in a family; Strokes on a golf hole; TV sets owned
Continuous: Amount of income; tax paid; • Weight of a student; • Yearly rainfall in Tampa, FL

Levels of Measurement
Distinguish among the nominal, ordinal, interval, and ratio levels of measurement.

For the nominal level of measurement observations of a qualitative variable can only be classified and counted. There is no particular order to the labels.

Example: The classification of the six colors of M&M’s milk chocolate candies is an example of the nominal level of measurement.

Nominal: Data may only be classified; Jersey numbers of football players • Make of car

The next higher level of data is the ordinal level.

Example: Each student in the class answered the question “Overall, how did you rate the instructor in this class?”

Ordinal: Data are ranked; Your rank in class...