1. Graphs

2.  Graphs are used to present numerical information in picture form.  Two common types of graphs are bar graphs and broken-line graphs. New Car Sales Number of Cars Month

3. Components of a Graph  Title  Every graph must have a title  Subtitles  Explains what the horizontal and vertical quantities represent  Equally spaced divisions

4. Example  Looking at the graph, how many more cars were sold in April than were sold in January? Number of Cars Month New Car Sales

5.  The daily high temperatures recorded during the week were as follows: Monday, 86ºF, Tuesday, 80ºF, Wednesday, 75ºF, Thursday, 82ºF, Friday, 88ºF, Saturday, 74ºF, and Sunday, 84ºF. Make a bar graph and a broken-line graph that present this information.

6.  Another type of graph is the pie graph.  It is also very important to label to the pie graph so that it can be understood.

7. Do It Yourself!  In this graph, what is the average number of type B cars sold in the 3 years shown? Annual Car Sales Number of cars (in thousands) Year

8. Histogram  A histogram is a bar graph that shows data in groups, or intervals.  It is often made from data displayed in a frequency table. ScoreCount0-91 10-192 20-293 30-394 40-495 50-594 60-693 70-792 80-892 90-991 Frequency Table Histogram

9. Example  Which category represents about 30% of the total number of books? 1- 5 6- 10 11- 15

10.  Scatter Plot is a graph of two related sets of data on an XY axis.  These are useful when you want to study related pairs, such as height and weight.

11.  Correlation is the relationship between two or more things.  Linear correlation is a scatter plot that forms a “line” showing that one axis seems to depend on or relate to the other.

12. Linear Correlations Positive linear correlation Negative linear correlation

13. Linear Correlation No correlation Constant correlation

14. Line of Best Fit  Line of best fit- line that seems to describe the direction the points are heading in There are methods for determining where this line is, but for our purposes we'll use just two criteria to find and draw the line: - The line of best fit must more or less follow the direction of the points. - There should be roughly the same number of points on each side of the line.  Lines of best fit can be used to predict results, especially if you find the line's equation. We'll look at this in more detail later.

15. Example of Line of Best Fit

16. Example  To find out an approximate income for someone who is 51 years old, we read the value from the graph: - Find age 51 on the x-axis. - Draw a vertical line up to the line of best fit. - Draw a horizontal line from there, back to the y-axis. This gives us the income of someone who is 51 years old... approximately $61,500.

17. Misleading Graphs  http://www2.fiu.edu/~graphing/mislead3.h tm http://www2.fiu.edu/~graphing/mislead3.h tm http://www2.fiu.edu/~graphing/mislead3.h tm  http://www.northcanton.sparcc.org/~techn ology/excel/files/misleading_graphs.html http://www.northcanton.sparcc.org/~techn ology/excel/files/misleading_graphs.html http://www.northcanton.sparcc.org/~techn ology/excel/files/misleading_graphs.html  http://www.bbc.co.uk/schools/gcsebitesiz e/maths/data/representingdata2rev5.shtm l http://www.bbc.co.uk/schools/gcsebitesiz e/maths/data/representingdata2rev5.shtm l http://www.bbc.co.uk/schools/gcsebitesiz e/maths/data/representingdata2rev5.shtm l