Elementary Statistics

Statistics

The study of how to collect, organize, analyze, and interpret data

Descriptive

To collect and summarize data

Individual

Person/object you want to know more about

Population

Collection of individuals all under the study

Sample

A subset of the population

Census

Getting everyone in the population that’s existed

Parameter

A numerical characteristic of a population (unknown)

Statistics

A number calculated from a sample (known)

Variable

Characteristic/measurement that can be determined for each individual in the population

Data

Literal values (a number)

Qualitive (categorical)

Word/Name that describes the quality of the individual

Quantitative (numerical)

Actual values, numbers, and counting

Ordinal

Can be ordered (qualitative)

Nominal

Cannot be ordered (qualitative)

Discrete

Counting, only certain values, checkpoints (quantitative)

Continuous

Measuring, all the values, the journey (quantitative)

Simple Random Sample (best)

Every member of population has an equal chance of beign chosen

Systematic

Randomly choose starting point, then survey every nth individuals

Stratified

Divide population into groups and randomly choose the number of individuals in each group

Cluster

Divide population into groups and randomly choose number of groups and survey all

Convenience Sample (worst)

Use results that are easiest to get around you

Pie chart

Chart representing data as slices of a circle, illustrating proportions

Bar graph

Chart that uses rectangular bars to represent the frequency or number of different categories

Stem & Leaf

A method of displaying quantitative data that uses stems to represent the leading digits and leaves for the trailing digits

Box plots

A graphical representation of the distribution of numerical data through Q1, Q3, the median, upper, and lower limit

Dot plots

A graphical display of data using dots to represent individual data points

Histogram

A graphical representation of the distribution of numerical data using bars to show the frequency of data within specified intervals.

Population mean

(µ) Sum the numbers, count the values, divide the sum by the count

Sample mean

(x̅) Sum the numbers, count the values, divide the sum by the count

Median

Arrange the numbers (smallest to largest), count until you get to the middle