Graphing Section 1.3

Why use graphs? Graph- used to make data easier to read and understand- shows patterns and trends

What is a graph? Visual display of information or data X-axis- horizontal- independent variable Y-axis- vertical- dependent variable Must have labels for each axis, a title, and units if appropriate You must select the proper scale. Don’t make the scale too large or too small Make sure you can read the data easily

Examples of Proper Scale and Improper Scale

Types of Graphs Line, Bar, Pie Line Graph Shows relationship between dependent and independent variable- often shows change over time Can compare more than one event as long as scale is the same Used most often in this class and science in general

Reading Line Graphs

Linear Relationships- makes a straight line both sets of numbers increase both sets of numbers decrease one set increases while the other set decreases one set of numbers increases while the other stays exactly the same one set of numbers decreases while the other stays exactly the same.

Reading Graphs Interpolation- reading between data points Extrapolation- reading beyond data points Less reliable than Interpolation Maybe something unexpected occurs after known data points

Problems with graphs You might use the wrong scale Don’t put two different units on the same graph- like Celsius and Fahrenheit or Celsius and Kelvin Can be used to distort data- maybe the scale is manipulated to make something seem worse than it is or not as bad as it is

Bar Graph + Circle/ Pie Bar: Compare information collected by counting Example: Comparison of how many in this class like which cookies. Try it. Circle/Pie: Shows how something can be broken down into parts Shows percents

Making Circle/Pie Graphs Use our cookie data: Determine % of each category Multiply % by 360 Gives you degrees of the circle Make Graph- will need protractor and compass