Statistics
a group of methods used to collect, analyze, and interpret data and to make decisions
Descriptive Statistics
consists of methods for organizing displaying and describing data by using tables, graphs, and summary measures
Inferential Statistics
consists of methods that use sample results to help make decisions or predictions about a population
Population
consists of all elements - individuals, items, or objects - whose characteristics are being studied. The population that is being studied is also called the target population
Sample
portion of the population selected for study
Census
survey that includes every number of the population
Sample survey
technique of collecting information from a portion of the population
Representative sample
sample that represents the characteristics of the population as closely as possible
Random sample
sample drawn in such a way that each element of the population has chance of being selected
Simple random sample
if the chance of being selected is the same for each element of the population
element/member
specific subject or object about which the information is collected
Variable
characteristic under study that assumes different values for different elements
Constant
value is fixed
Observation/measurement
value of a variable for an element
Data set
collection of observation on one or more variables
Quantitative variable
variable that can be measured (discrete variables/continuous variable)
Discrete variable
variable whose values are countable...no intermediate values
Continuous Variable
variable that can assume any numerical value over a certain interval
Qualitative/Categorical Variable
variable that cannot assume a numerical value but can be classified into two or more nonnumeric categories
Cross Section Data
data collected on different elements at the same point in time
Time-series data
data collected on the same element for the same variable at different points int time