# Lesson 4: Displaying Public Health Data

## Self-Assessment Quiz

Now that you have read Lesson 4 and have completed the exercises, you should be ready to take the self-assessment quiz. This quiz is designed to help you assess how well you have learned the content of this lesson. You may refer to the lesson text whenever you are unsure of the answer.

Unless otherwise instructed, choose ALL correct choices for each question.

- Tables and graphs are important tools for which tasks of an epidemiologist?
- Data collection
- Data summarization (descriptive epidemiology)
- Data analysis
- Data presentation

- A table in a report or manuscript should include:
- Title
- Row and column labels
- Footnotes that explain abbreviations, symbols, exclusions
- Source of the data
- Explanation of the key findings

- The following table is unacceptable because the percentages add up to 99.9% rather than 100.0%

Age group No. Percent < 1 year 10 19.6 1–4 9 17.6 5–9 9 17.6 10–14 17 33.3 __≥15____6____11.8__Total 53 - True
- False

- In the following table, the total number of persons with the disease is:

Cases Controls Total Total 25 25 50 Exposed 22 12 34 Unexposed 3 13 16 - 3
- 22
- 25
- 34
- 50

- A table shell is the:
- Box around the outside of a table
- Lines (“skeleton”) of a table without the labels or title
- Table with data but without the title, labels or data
- Table with labels and title but without the data

- The best time to create table shells is:
- Just before planning a study
- As part of planning the study
- Just after collecting the data
- Just before analyzing the data
- As part of analyzing the data

- Recommended methods for creating categories for continuous variables include:
- Basing the categories on the mean and standard deviation
- Dividing the data into categories with similar numbers of observations in each
- Dividing the range into equal class intervals
- Using categories that have been used in national surveillance summary reports
- Using the same categories as your population data are grouped

- In frequency distributions, observations with missing values should be excluded.
- True
- False

- The following are reasonable categories for a disease that mostly affects people over age 65 years:

__Age Group__

< 65 years

65–70

70–75

75–80

80–85

85- True
- False

- In general, before you create a graph to display data, you should put the data into a table.
- True
- False

- On an arithmetic-scale line graph, the x-axis and y-axis each should:
- Begin at zero on each axis
- Have labels for the tick marks and each axis
- Use equal distances along the axis to represent equal quantities (although the quantities measured on each axis may differ)
- Use the same tick mark spacing on the two axes

- Use the following choices for Questions 12a–d:
- Arithmetic-scale line graph
- Semilogarithmic-scale line graph
- Both
- Neither

- ____ A wide range of values can be plotted and seen clearly, regardless of magnitude
- ____ A constant rate of change would be represented by a curved line
- ____ The y-axis tick labels could be 0.1, 1, 10, and 100
- ____ Can plot numbers or rates

- Use the following choices for Questions 13a–d:
- Histogram
- Bar chart
- Both
- Neither

- ____ Used for categorical variables on the x-axis
- ____ Columns can be subdivided with color or shading to show subgroups
- ____ Displays continuous data
- ____ Epidemic curve

- Which of the following shapes of a population pyramid is most consistent with a young population?
- Tall, narrow rectangle
- Short, wide rectangle
- Triangle base down
- Triangle base up

- A frequency polygon differs from a line graph because a frequency polygon:
- Displays a frequency distribution; a line graph plots data points
- Must be closed (plotted line much touch x-axis) at both ends
- Cannot be used to plot data over time
- Can show percentages on the y-axis; a line graph cannot

- Use the following choices for Questions 16a–d:
- Cumulative frequency curve
- Survival curve
- Both
- Neither

- ____ Y-axis shows percentages from 0% to 100%
- ____ Plotted curve usually begins in the upper left corner
- ____ Plotted curve usually begins in the lower left corner
- ____ Horizontal line drawn from 50% tick mark to plotted curve intersects at median

- A scatter diagram is the graph of choice for plotting:
- Anabolic steroid levels measured in both blood and urine among a group of athletes
- Mean cholesterol levels over time in a population
- Infant mortality rates by mean annual income among different countries
- Systolic blood pressure by eye color (brown, blue, green, other) measured in each person

- Which of the following requires more than one variable?
- Frequency distribution
- One-variable table
- Pie chart
- Scatter diagram
- Simple bar chart

- Compared with a scatter diagram, a dot plot:
- Is another name for the same type of graph
- Differ because a scatter diagram plots two continuous variables; a dot plot plots one continuous and one categorical variable
- Differ because a scatter diagram plots one continuous and one categorical variable; a dot plot plots two continuous variables
- Plots location of cases on a map

- A spot map must reflect numbers; an area map must reflect rates.
- True
- False

- To display different rates on an area map using different colors, select different colors that have the same intensity, so as not to bias the audience.
- True
- False

- In an oral presentation, three-dimensional pie charts and three-dimensional columns in bar charts are desirable because they add visual interest to a slide.
- True
- False

- A 100% component bar chart shows the same data as a stacked bar chart. The key difference is in the units on the x-axis.
- True
- False

- When creating a bar chart, the decision to use vertical or horizontal bars is usually based on:
- The magnitude of the data being graphed and hence the scale of the axis
- Whether the data being graphed represent numbers or percentages
- Whether the creator is an epidemiologist (who almost always use vertical bars)
- Which looks better, such as whether the label fits below the bar

- Use the following choices for Questions 25a–d (match all that apply):
- Grouped bar chart
- Histogram
- Line graph
- Pie chart

- ____ Number of cases of dog bites over time
- ____ Number of cases of dog bites by age group (adult or child) and sex of the victim
- ____ Number of cases of dog bites by breed of the dog
- ____ Number of cases of dog bites per 100,000 population over time

Page last reviewed: May 18, 2012