Critique Ways in Which Data is Presented

1. Critique Ways in Which Data is Presented Main Resource: Statistics Canada Website

2. Information: Use in society • You have probably heard of the term the information age. It describes how modern society depends on information as a resource. People rely on information to make decisions and recommendations in many fields, including politics, economics, environment and entertainment. • Without reliable information, people can make poor decisions that sometimes result in serious consequences.

3. Why we need to be critical • Since the media plays an immense part in our daily life and they are continually giving us information (data). • Data analysis is often used in advertising, forecasting, and public policy. The media is full of representations of data (i.e. Graphs or tables) to support statistical claims. • We need to be critical to: • Know what is relevant • Know what is important • Know what is true • Know what is biased • Identify misinformation • Etc.

4. What is a graph? • A graph is a visual representation of a relationship between, but not restricted to, two variables. • Graphs are effective visual tools because they present information quickly and easily. It is not surprising then, that graphs are commonly used by print and electronic media.

5. Different type of graphs • Circle graphs • Line graphs • Bar graphs • Double bar graphs • Pictographs

6. Circle graphs (pie charts) • A circle graph displays data as a percentage of the whole. Each pie section should have a label and percentage. A total data number should be included.

7. Line Graphs • A line graph plots continuous data as points and then joins them with a line. Multiple data sets can be graphed together, but a key must be used.

8. Bar graphs and double bar graphs • A bar graph displays discrete data in separate columns. A double bar graph can be used to compare two data sets. Categories are considered unordered and can be rearranged alphabetically, by size, etc.

9. Pictographs • A pictograph uses an icon to represent a quantity of data values in order to decrease the size of the graph. A key must be used to explain the icon.

10. Misinterpretation of information • Misinterpretation is a common problem when using statistical information. It may be caused by a number of factors. • Misunderstanding the data • Using incomparable definitions • Deliberately misinterpreting the information

11. Activity • In groups of 2 or 3, come get a worksheet and answer the questions. • You will need to prepare a short presentation about your topic (based on your worksheet) to present to the class.

12. Circle graphs (pie charts) • Advantages • Visually appealing • Shows percent of total for each category • Disadvantages • No exact numerical data • Hard to compare 2 data sets • "Other" category can be a problem • Total unknown unless specified • Best for 3 to 7 categories • Use only with discrete data

13. Line Graphs • Advantages • Can compare multiple continuous data sets easily • Interim data can be inferred from graph line • Disadvantages • Use only with continuous data

14. Bar graphs and double bar grpahs • Advantages • Visually strong • Can easily compare two or three data sets • Disadvantages • Graph categories can be reordered to emphasize certain effects • Use only with discrete data

15. Pictographs • Advantages • Easy to read • Visually appealing • Handles large data sets easily using keyed icons • Disadvantages • Hard to quantify partial icons • Icons must be of consistent size • Best for only 2-6 categories • Very simplistic

16. Deliberately misinterpreting information Look at the effect of not starting the y-axis of 0. It is important to start graphs at 0.

17. Deliberately misinterpreting information Look at this pictograph. It looks like there are more horses. It is important that all the pictures are the same size.

18. Deliberately misinterpreting information Why does Graph A look different than Graph B? Both the graphs represent the same data.

19. Deliberately misinterpreting information The graphs look different due to the different vertical scales. Graph A appears to show a more rapid decrease in sales than graph B.