Statistics: The Science of collecting, classifying, organizing, summarizing, analyzing, presenting, and
interpreting data to make informed scientific decisions
Branches of stats
1. Descriptive
a. Organizing
b. Summarizing data
c. Presenting data in an informative way
2. Inferential
a. Determining something about pop. based on a sample
b. Methods for making decisions/predictions and drawing conclusions about the population.
Probability vs Inference: Relationship between population and sample
Terms
★Population: a collection of all units that were interested in studying
★Sample: a representative subset of the population
★Census: Collection of data from every member of the population
★Parameter: A numerical value that summarizes a characteristic of the entire population
(PERCENTAGE)
★Statistic: a numerical value that summarizes the data from a sample
★Unit/Subjects: The entity that is being observed
★Variable: a characteristic about each element of a population/sample
★Data: What was collected from the study
Variables
❖Qualitative/Categorical
➢Nominal - No rank or order
➢Ordinal - Natural order
❖Quantitative/Numerical
➢Discrete - Counted items
➢Continuous - measures items
❖Associated/Dependent variable: Two variables show a connection in some way
❖Independent Variables: Two Variables show no connection
Sampling Principles & Strategies
★With Replacement: a member of the pop can be chosen more than once
★Without Replacement: a member of the population is only selected once
★Random: Each member has an equal chance of being selected
★Nonrandom
Methods
1. Simple Random Sampling (SRS)
2. Stratified Random Sampling
