Graphing in Science

Types of Charts  Most scientific graphs are made as line graphs.  However, occasionally bar graphs, pie charts, or scatter plots are used.

Why do we use graphs?  All types of graphs and charts make trends in data easier to see.  It is a way for scientists to analyze their data.  It can also be used to predict data that is not measured on the graph.

Steps to constructing a line graph  Identify your variables  Independent variable goes on the x-axis  Dependent variable goes on the y-axis  Determine the variable range  Subtract the lowest data value from the highest data value for each variable  Determine the scale of the graph  This is the numerical value for each square that best fits the range of each variable  Use most of the graphing space available.

Steps to constructing a line graph (continued)  Number and Label each axis  Do not forget to include units!!  Plot the data points.  Draw the graph  Connect the dots  Best Fit  Title the graph  Titles should clearly show what the graph is about  If you have more than one set of data, you need to include a key to identify the different lines

Example Using the data table, answer the questions below:  What is the independent variable?  pH of the water  What is the dependent variable?  Number of tadpoles  What goes on the x-axis? What is the range?  pH of water (2.5)  What goes on the y-axis? What is the range?  Number of tadpoles (65) pH of water# of tadpoles

Example pH of water# of tadpoles