The Basics of Reading Tables, Graphs, and Charts

Tables
Tables present data in rows and columns.

Here's a very simple table that shows the number of accidents reported in one county over a 24-hour period.

Use it to answer the question that follows.

1. Based on the information provided in this table, at what time of day do the most accidents occur?

The correct answer, of course, is b, morning rush hour. You can clearly see that the highest number of accidents (11) occurred between 6:00 A.M. and 9:00 A.M.

Graphs
Now, here's the same information presented as a graph. A graph uses two axes rather than columns and rows to create a visual picture of the data:


Here you can actually see the time of greatest number of accidents represented by a line that corresponds to the time of day and number. These numbers can also be represented by a box in a bar graph, as shown on the next page.


The key to reading graphs is to be sure that you know exactly what the numbers on each axis represent.

Otherwise, you're likely to grossly misinterpret the information. Here, you see that the horizontal axis represents the time of day and the vertical axis represents the number of accidents that occurred. Thus, the tallest box shows the time of day with the most accidents.

Questions on tables, charts, and graphs may also ask you to make inferences and maybe even do basic math using the information and numbers the table, chart, or graph supplies.

For example, you maybe asked questions like the following on the information presented in the table, line graph, or bar graph above. The answers follow immediately after the questions.
2. What is the probable cause for the high accident rate between 6A.M. and 9 A.M.? a. People haven't had their coffee yet. b. A lot of drivers are rushing to work. c. Sun glare. d. Construction.
3. What is the total number of accidents? a. 48 b. 51 c. 49 d. 53
2. b. A question like this tests your common sense as well as your ability to read the graph. Though there may indeed be sun glare and though many drivers may not have had their coffee, these items are too variable to account for the high number of accidents. In addition, d, construction, is not logical because construction generally slows traffic down. Answer b is the best answer, because from 6:00 to 9:00 A.M. there is consistently a lot of rush hour traffic. In addition, many people do rush, and this increases the likelihood of accidents.
3. c. This question, of course, tests your basic ability to add. To answer this question correctly, you need to determine the value of each bar and then add those numbers together.

Charts
Finally, you may be presented information in the form of a chart like the pie chart on the next page. Here the accident figures have been converted to percentages. In this figure you don't see the exact number of accidents, but you see how accidents for each time period compare to the others.



 

Practice
Try the following questions to hone your skill at reading tables, graphs, and charts.
Answer questions 1 and 2 on the basis of the graph shown below.

Causes of household fires, in percentages


1. What is the percentage of smoking-related fires? a. 26 b. 32 c. 58 d. 2658
2. Based on the information provided in the chart, which of the following reasons applies to the majority of these fires? a. malicious intent to harm b. violation of fire safety codes c. carelessness d. faulty products

Answer questions 3 and 4 on the basis of the graph shown below.

Number of sick days per year of employment


3. At what point does the rate of increase of sick days change? a. 4 years of employment b. 10 years of employment c. 8 years of employment d. 12 years of employment
4. During what years of employment are the number of sick days equal to double the number of years of employment? a. 1,4, and 12 b. 13,14,and 15 c. 1, 2, and 15 d. 2, 4, and 10

Answers and Explanations to Practice Exercise
1. d.Of the causes presented in the chart, both cigarettes (26 percent) and matches (32 percent) are related to smoking. But not all match fires are necessarily smoking related. Thus, the best answer allows for a range between 26 percent and 58 percent.
2. c. Fires from cigarettes, heaters, irons, and matches81 percent in totalare generally the result of carelessness. Only 4 percent of fires are arsons, so a cannot be correct. Electrical, heater, and explosion fires may be the result of fire safety code violations, but even so, they total only 31 percent. Finally, there's no indication in this chart that there were faulty products involved.
3. b. In the first nine years, employees gain an additional two sick days every two years. At ten years of employment, however, the gain increases from two days every two years to four days, that is, from ten days in the eighth year to fourteen days in the tenth year.
4. c. In the first year, the number of sick days is two; in the second, four; and not until the fifteenth year does the number of sick days (thirty) again double the number of years of employment.