1. A pie chart is used to show how something is divided or shared by displaying data as a circle divided into sectors proportional to the quantities. 2. To calculate angles and frequencies from a pie chart, you take the angle/frequency for a category and divide it by the total to get the proportional amount. 3. A histogram is similar to a bar chart but used for continuous numerical data, with bars of unequal widths to show frequency density on the y-axis rather than just frequency.

1. Why pie charts?A pie charts is a good way of displaying data when you want to show how something is shared or divided.Rough grazingcropscropsPermanent grassWood landTowns and roadsLand use in the UK

2. How do we calculate angles?20 000 students took part in a survey on cheese10 566 students answered blue.10 566 x 360º = 190º (to 3 s.f.)20 000How do we calculate frequency (number of people) ?Measure the angle with a protractor if you are not given it.47º x 20 000 = 2610 people (to 3 s.f)360º….

3. Bar Charts (too easy)A bar chart is a chart where the height of bars represents the frequency. The data is 'discrete' (discontinuous- unlike histograms where the data is continuous)The bars should be separated by small gaps.Frequencyisalwaysonthe y-axis

4. HistogramsWhen the data is continuous (time, length, anything numerical) the graph is called a histogram.A histogram with equally spaced bars looks exactly like a bar chart.BUT you can draw histograms with bars of different widths and the area of the bar is what’s important. Frequency Density is the label for the y-axis. Frequency density = frequency class width ‹ VeryImportant…

5. 543frequency density25?01 1610893124570Distance (Miles)Example Question: The table shows the distance walked in kmsby some walkers at Collserollaat the weekend. Draw a histogram for the data.525  1 = 542  1 = 2312  3 = 41.253  1 = 31. The class widths are unequal so a frequency density column is needed.5  4 = 1.252. Scale the horizontal axis.3. Calculate frequency densities and scale the vertical axis.

6. 5Distance Walked by Walkers43frequency density21610893124570Distance (Miles)Example Question 2 The table shows the distance walked in kmsby some walkers at Collserollaat the weekend. Draw a histogram for the data.52431.254.Draw in the bars and title.

7. ScattergraphsWe use scattergraphswhenwehavetwo sets of data.Eg Are peoplewho are good at mathsalsogood at science?Are peoplewho are older, taller?Wehaveone set of valuesonthe x-axis and theotheronthe y-axis

8. Practice 1: Look at the following scatter diagrams. Do they have positive or negative correlation and what does that mean?1a) (b)Next

9. 2) The table lists the weights of twelve books and the number of pages in each one.On the grid, draw a scatter graph to show the information in the table.Draw a line of best fit on the graph and then describe the correlation between the number of pages in the book and their weight.How much would you expect a book of 120 pages to weigh?