Вивчаючи статистику

4. Read and translate the text:
You present categorical data by sorting responses by categories. The count, amount, or percentage (part of the whole) of responses by category is then placed into a summary table or into one of several forms of charts.
The Summary Table. A two-column table in which the names of the categories are listed in the first column and the count, amount, or percentage of responses are listed in a second column. Sometimes additional columns present the same data in two or more ways (for example, as counts and percentages).
EXAMPLE. Blood Donation Behavior by Americans
Behavior Percentage (%)
Donate regularly 11
Have donated and may again 31
Have not but may in future 17
Never have, never will 13
Want to, but think they cannot 28
This table summarizes the results of a blood donation behavior survey that was conducted during the American Red Cross Save a Life Tour1.
Summary tables enable you to see the big picture about a set of data. In the example, you can conclude that there seems a good opportunity to increase the percentage of people giving blood donations because only 11% donate regularly, and an equally small group (13%) say they will never donate.
The Bar Chart. A chart containing rectangles (“bars”) in which the length of each bar represents the count, amount, or percentage of responses of one category.
A bar chart better makes the point that the category “have donated and may donate again” is the single largest category for this example. For most people, scanning a bar chart is easier than scanning a column of numbers in which the numbers are unordered, as they are in the blood donation summary table.
The Pie Chart. A circle chart in which wedge-shaped areas—pie slices—represent the count, amount, or percentage of each category and the entire circle (“pie”) represents the total.
By ordering the categories carefully, you can make the point that a majority of those surveyed either want to donate but think they cannot or are people who have donated in the past and may do so again in the future.
Although you will probably produce most of your pie charts using computers or calculators, you can also produce a pie chart using a protractor to divide up a drawn circle. To produce a pie chart in this way, first calculate percentages for each category. Then multiply each percentage by 360, the number of degrees in a circle, to get the number of degrees for the arc (part of circle) portion of each category’s pie slice. (For example, for the “have donated blood regularly” category, multiply 11% by 360 degrees to get 39.6 degrees.) Mark the endpoints of this arc on the circle using the protractor, and draw lines from the endpoints to the center of the circle. (You may want to draw your circle using a compass so that the center of the circle can be easily identified.)