Chapter 1: Data and Statistics

In a poll of 50,000 randomly selected college students, 74% answered "yes" when asked "Do you have a television in your dorm room?" What is the sample?

50,000 selected students

Variable

A characteristic of interest for the elements

Sample survey

A survey to collect data on a sample

Census

A survey to collect data on the entire population

Examples of quantitative

Age, temperature

Two types of data

Categorial and Quantitative

Examples of Categorial

Gender, Hair Color, Bond Rating

Two types of Categorial data

Nominal and Ordinal

Two types of quantitative data

Ratio and Interval

Elements

The entities on which data are collected

In a poll of 50,000 randomly selected college students, 74% answered "yes" when asked "Do you have a television in your dorm room?" What is the population?

all college students

Nominal

classification data; no ordering

Population

collection of ALL individuals or items under consideration in a study

Simple Random Sampling

each possible sample is equally likely to be obtained

Example of ratio

height, weight, age, length

Example

m/f

Inferential

making predictions about a population based on sample

Ordinal

ordered but differences between values are not important

Interval

ordered, constant scale, but no natural zero; differences make sense, but ratios do not

Ratio

ordered, constant scale, natural zero

Descriptive

organizing and summarizing

Sample

part of the population from which the information is being obtained

Example of ordinal

restaurant ratings

Example of Interval

temperature