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