Lesson Overview Section
In Lesson 4 we continue our discussion of describing data through numerical summaries and also think about statistical pictures. An overview of some key questions addressed is given in the table below.
| Question Addressed | Statistical Summary |
|---|---|
| Where are values located along the number line? |
Median Mean |
| How variable are the numbers? |
IQR Standard Deviation |
| What is the relative standing of an individual value compared with other numbers on a list? |
Percentiles Standardized Scores |
| Question Addressed | Statistical Picture |
|---|---|
| How are all of the numbers on a list distributed over the number line? |
Dot plots Boxplots Histograms |
|
How is a categorical variable distributed? How do categorical variables compare? |
Bar graphs Comparative bar graphs |
| How do the distributions of two measurement variables compare? |
Comparative boxplots Comparative dotplots |
| How do percentages or averages change over time? | Line graph or time series plot |
| How are two measurement variables associated? | Scatterplot |
Objectives
After successfully completing this lesson, you should be able to:
- Interpret standard scores as a measure of relative standing on a list.
- Apply the relationship between standard scores and the percentiles of a normal distribution.
- Interpret graphs used with categorical data.
- Interpret scatter plots.
- interpret time series plots and recognize trends and seasonality.
- critique whether graphical presentations provide a fair summary of the data.