how do you draw pie charts?

Answer 1

Think of a circle.... cut it into pieces from the middle out to the edge, Think 'trivial pursuit'

Answer 2

In order to draw a pie chart, first you take a compass and draw a perfect circle. Then you would indicate the center point of the circle with your pencil (you know where the center point is because it's the indent that the pointed steel part of your compass made on the piece of paper). Then you use a protractor and straightedge to be able to cut the pie chart into sector's that will indicate exactly the percentages they are sopposed to.
Before you start this project, make sure (and this is extremely important if you want to get an exact pie chart) that the radius of the circle you're drawing with your compass equals the radius of the protractor that you're using. The radius of your protractor is from the center of the straightpart of it at the bottom to one of the endpoints of the straightpart of it at the bottom. So, you take your compass and put it's pointy metal piece at the center of the protractors straight part, then, keeping it there, move the pencil of the compass to one of the endpoints of the straight part of the protractor and make sure that the pencils point touches that endpoint. Then you have made your compass equal the radius of the protractor. So you would then draw the circle with the compass, not altering it's radius at all, then the circle that you drew and your protractor would be exactly compatible.
Since there are 180 degrees in a semi-circle (which is what a protractor is), and the semi-circle of your pie chart measure's, of course, fifty percent (half of the pie chart), you would divide 180 by 50, which is, 3.6. Therefore, when you multiply 3.6 times 100, you get 360, the degree measure of a circle. This shows us that 3.6 degrees, in a pie chart, represent one percent.
So, say your pie chart was 20%, 30%, and 50%. You'd draw a complete circle with your compass, indicate the center point of the circle, then multiply 20 by 3.6 degrees, which is 72 degrees. Therefore you'd draw a 72 degree angle with your protractor on the circle, then, with your straightedge, you'd draw two line segments, the first you'd draw from the center of the circle to one of the endpoints of the 72 degree arc, then the other one would be from the center of the circle to the other endpoint of the 72 degree arc. Then you'd have 20% represented exactly on your pie chart.
You'd then use the same process for the other percents, just using the different numbers. When your done, you'll have an exact pie chart representing 20%, 30%, and 50%. You can use this method for an infinite amount of pie charts (in other words, this method will work for any pie chart).
There you go. I'm glad I could help. :)

Answer 3

Firstly, you need the following: an Angle measurer, a pencil, a ruler and a compass.

First things first,

1) Draw a circle.
2) Mark the centre, and draw a straight line (a reference line) from the centre of the circle to the edge of the circle.
3) Still with me? good
4) Now the next bit is the tricky bit


Now, the best way to do this is give you an example.

I have a bag of 9 apples, 18 banannas and 27 pears. So how do I draw represent this on a pie-chart?

5) count the total number of fruits (i.e. the total number in the data set). In this case it is 9+18+27=54.

6) now consider each of the fruits. Since there are 3 fruits, your pie chart will consist of 3 parts! So if there were 7 fruits, the pie chart would consist of 7 parts and so on.

7) Back to the example. Now what you do is

*Divide each of the fruit-numbers in turn by 54,
*then multiply this number by 360.

i) So for the Apples, I do
*9 divided by 54 = 0.1666... ,
*then I do 0.1666... multiplied by 360.

This gives me 60 degrees. This answer represents the angle that you should draw on your circle.

Now use your angle measurer to measure an angle of 60 degrees on the circle, using the reference line drawn in part one as a reference line.

i.e. draw a new straignt line from the centre of your circle to its edge so that the angle between the two lines is 60 degrees

Now this marks the portion of your pie-chart representing your apples!

NOTE: now for the other fruits, the 'reference line' is always the 'last' line drawn! and so on

ii) Similarly
*for Banannas (The angle you get should be 180 degrees)
*for Pears (The angle should be 120 degrees)

8) To check to see if your pie chart is correct, add up the calulated angles- if they add up to 360 then chances are your okay!


Now colour in each of the sections, make a seperate key (showing which colour represents which fruit) and your done.

Hope this helps

Answer 4

Consider the case where £100 is to be shared as follows:-

BILL: £40
JIM: £35
BEN: £25

The angles are calculated :-

BILL: 40/100 x 360° = 2/5 x 360° = 144°
JIM: 35/100 x 360° = 126°
BEN: 25/100 x 360° = 90°

Total = 360° as a check

Angles have then to be drawn on a pie chart:-

1) draw a circle with centre O and horizontal
radius OB.

2) Use protractor to construct angle BOA where angle BOA = 144°. Label this sector as BILL

3) Use protractor to construct angle AOC where
angle AOC = 126°. Label this sector as JIM

4) Remaining sector is that of BEN and is so labelled.

Above the pie chart it would be helpful to say TOTAL = £100.
Alongside the pie chart write BILL ---£40,JIM --- £35 and BEN --- £25.

I hope that this example is of assistance.

Answer 5

Draw a circle on a piece of paper with a compass and pencil.

Look at the percentages you have for each answer...

For example...in our playground survey we asked 100 people 'which was their favourite pet'

20 people liked cats, so this translates to 20%
42 people liked dogs, so this translates to 42%
15 people liked sharks, so this translates to 15%
9 people liked iguanas, so this translates to 9%
etc...
You have to translate this information into the pie chart.

Imagine cutting it up to share between all of those people who took part in your 'survey' The 'cat' people would get 20% of the chart, the dog people would get 42% of the chart etc.

There are 360 degrees in a full circle. (You will need a protractor to help you with this bit). 360 degrees divided by 100 people in the survey equates to 3.6 degrees per person.

Draw a line from the centre of the pie chart (compass hole) to the outside of the circle. It can be anywhere.

So if the cat lovers were 20%, the correct measurement from your first line would be 20x3.6 degrees. Mark out 72 degrees round the outside of the 'pie' with the protractor and draw a line to the centre.. This represents 20% of the pie chart for this survey. Colour this section in and label it 'cat lovers'.

Dog lovers were 42%. So this is 42x3.6 degrees. Starting from where the cat lovers finished, place your protractor onto the chart and measure a further 151 degrees around the outside of the chart. Get your pen and draw a line to the middle of the pie. This now represents 42% of the pie. Again, colour it in with a different pen and label it 'dog lovers'.

Do the same with the 'shark lovers' section and all of the rest of the answers in your survey.

If you get many answers that only represent a small amout of information, it is worth lumping all these togeter and labelling them 'others'

This is the most simple way of doing pie charts manually. Or, you can always get the computer to do one for you.

Answer 6

A pie chart is a circular chart divided into sectors, illustrating relative magnitudes or frequencies. In a pie chart, the arc length of each sector (and consequently its central angle and area), is proportional to the quantity it represents. Together, the sectors create a full disk. A chart with one or more sectors separated from the rest of the disk is called an exploded pie chart.


One of William Playfair's piechart in his Statistical BreviaryWhile the pie chart is perhaps the most ubiquitous statistical chart in the business world and the mass media, it is rarely used in scientific or technical publications.[1] It is one of the most widely criticised charts,[2] and many statisticians recommend to avoid its use altogether[3][4], pointing out in particular that it is difficult to compare different sections of a given pie chart, or to compare data across different pie charts. While pie charts can be an effective way of displaying information in some cases, in particular when the slices represent 25 or 50% of the data,[5] in general, other plots such as the bar chart or the dot chart are more adapted for representing information.

The earliest known pie chart is generally credited to William Playfair's Statistical Breviary of 1801.


Example

A pie chart for the example data.
An exploded pie chart for the example data, with the largest party group exploded.The following example chart is based on preliminary results of the election for the European Parliament in 2004. The following table lists the number of seats allocated to each party group, along with the percentage of the total that they each make up. The values in the last column, the central angle of each sector, is found by multiplying the percentage by 360°.

Group Seats Percent (%) Central angle (°)
EUL 39 5.3 19.2
PES 200 27.3 98.4
EFA 42 5.7 20.7
EDD 15 2.0 7.4
ELDR 67 9.2 33.0
EPP 276 37.7 135.7
UEN 27 3.7 13.3
Other 66 9.0 32.5
Total 732 99.9* 360.2*

*Because of rounding, these totals do not add up to 100 and 360.

The size of each central angle is proportional to the size of the corresponding quantity, here the number of seats. Since the sum of the central angles has to be 360°, the central angle for a quantity that is a fraction Q of the total is 360Q degrees. In the example, the central angle for the largest group (EPP) is 135.7° because 0.377 times 360, rounded to one decimal place, equals 135.7.
Warning against usage

The same data plotted using a pie chart and a bar chart.Pie charts should be used only when the sum of all categories is meaningful, for example if they represent proportions.

Pie charts are rare in the scientific literature, but are more common in business and economics. One reason for this may be that it is more difficult for comparisons to be made between the size of items in a chart when area is used instead of length. In Stevens' power law, visual area is perceived with a power of 0.7, compared to a power of 1.0 for length. This suggests that length is be a better scale to use, since perceived differences would be linearly related to actual differences.

In research performed at AT&T Bell Laboratories, it was shown that comparison by angle was less accurate than comparison by length. This can be illustrated with the diagram to the right, showing a pie chart and a bar chart for the same data side to side. Most subjects have difficulty ordering the slices in the pie chart by size; when the bar chart is used the comparison is much easier

Answer 7

i take advantage of Excel; put on your documents right into a table and theres a small button on the toolbar that you press and this technique actually attracts a graph for you - then you could substitute one among those graph to a pie chart.

Answer 8

draw a circle of any measure and with a protractor mark the degrees

Answer 9

With a compass and rule.
This link may be of help.
http://www.chartexample.com/chart_example/piechart.php

Answer 10

You should just follow your heart