Introduction to Statistics and Types of Variables

Statistics

organize and summarize data
draw inferences about data when only partly observed

Element

individual for whom the information is collected

Variable

characteristic about each element

Data (singular)

value of a variable associated with one element

point in a column or row

Variable (many)

set of singular data values collected for variable

whole column or row

Dataset

the entire data collected

Database

program/tool used for data entry

Descriptive statistics

describe, organize,summarize,display,data collected for experiment or event
nominal and ordinal variables

Inferential Statistics

used to make predications about a larger population based on a sample population

Quantitative methods

testing theories using numbers
aka continuous variables
ratios or intervals (scale)

Qualitative methods

testing theories using language
aka categorical or discrete variables
nominal or ordinal

Variable

characteristic or measureable property that can change from one observation to another

Nominal Variable

classifies data into distinct categories with no order of ranking

descriptive categories

Continuous or Quantitative Variable representation

pie or bar charts

Ordinal Variable

categorical variable where the order of the values matters

ranked categories

Qualitative or categorical or discrete variable representation

histograms

Interval variable

central characteristic that can be measured along a numbered continuum

has a numerical value meaning 0 is not possible or absolute

Ratio

numbers represent fixed measurement units with meaningful relationships

value of 0 serves as reference point

Measurement hierarchy (weak to strong)

nominal —> ordinal —> scale

Independent Variable

changed by person doing the experiment

aka predictor shown on x-axis

Dependent Variable

measured in the experiment

aka response criterion outcome

shown on y-axis

highly fluxuates

Cofounders

all the variables that stay the same in an experiment

aka covariates