Basic Definitions Flashcards
Statistics
The study of methods for collecting, organizing, and analyzing data
Descriptive Statistics
Procedures used to organize and present data in a convenient and communicable form
Inferential Statistics
Procedures employed to arrive at broader conclusions or inferences about populations on the basis of samples
Population
The complete set of actual or potential elements about which inferences are made
Sample
A subset of the population selected using some sampling method
Sampling Methods
Cluster Sample, Stratified Sample, Simple Random Sample
Cluster Sample
A population is divided into groups called ______s; some ______s are randomly selected, and every member in them is observed
Stratified Sample
A population is divided into strata, and a fixed number of elements of each stratum are selected for the sample
Simple Random Sample
A sample selected so that each possible sample of the same size has an equal probability of being selected; used for most elementary inference
Variable
An attribute of elements of a population or sample that can be measured (Ex:height, weight, hair color, IQ, and pulse rate are some of the many of these that can be measured for people)
Data
Values of variables that have been observed
Types of Data
Qualitative/Categorical, Quantitative, Discrete, and Continuous Data
Qualitative/Categorical Data
descriptive but not numeric (Ex: gender, birthplace, color of a car)
Quantitative Data
take numeric values
Discrete Data
take counting numbers (0, 1, 2, …) as values, usually representing things that can be counted (Ex: number of fleas on a dog, number of times a professor is late in a semester)
Continuous Data
can take a range of numeric values, not just counting numbers – measures (Ex: height of a child, weight of a bag of beans, amount of time a professor is late)
Levels of Measurement for Qualitative/Categorical Data
Nominal and Ordinal Levels
Nominal Level
Values are just names, without any order (Ex: color of a car, major in a college)
Ordinal Level
Values have some Natural Order (Ex: Military Rank, High School Class [Freshmen, Sophomore, Junior, Senior])
Levels of Measurement for Quantitative Data
Interval and Ratio Levels
Interval Level
Numeric data w/ no natural zero point; intervals (differences) are meaningful, but ratios are not (Ex: temperature in Fahrenheit degrees – 80 degrees F is 20 degrees F hotter than 60 degrees F, but it is not 150% as hot)
Ratio Level
Numeric data for which there is a true zero; both intervals and ratios are meaningful (Ex: weight, length, duration, most physical properties really)
Statistic
A numeric measure computed from sample data, used to describe the sample and to estimate the corresponding population parameter
Parameter
A numeric measure that describes a population; usually not computed, but inferred from sample statistics
