Chapter 2 Flashcards
Data
Facts that convey information
Two parts of Data
Observation and variable
Variable
Name for what is being counted, measured, or observed
Observations
Actual data values observed
Variation
Observations vary
Data Distribution
Pattern summarizing variation
Two main types of Quantitative Variables
Discrete and Continuous
Two main types of Categorical (Qualitative) Variables
Ordinal and Nominal
Discrete
Possible values belong to a set of distinct numbers
Continuous
Possible values belong to an interval (such as 10-50) and can take on any value in that interval.
Ordinal
Ordered categories (education levels)
Nominal
Un-ordered categories (color, marital status)
Two notes on Variable types
A continuous variable may be simplified into a Categorical one for short
What is a Bar Chart used for?
Displaying Categorical variables
Bar Chart x-axis
Categories or classes
Bar Chart y-axis
Count (frequency) or relative frequency
Relative Frequency for sample size n
A percent value find by dividing the frequency of a given class by the sample size (A/n, B/n, …)
What does using Relative Frequency change in a Bar Chart?
Only the y-axis quantities to percents; proportionally the chart remains unchanged
What is a Frequency Histogram used for?
Displaying quantitative variables
Frequency Histogram x-axis
Intervals (bins)
Frequency Histogram y-axis
Counts (frequency) or relative frequency
Sturge’s Rule

Two main types of Variables
Quantitative and Categorical (Qualitative)
Quantitative
Observations which take on numerical values


