GRAPHING Variables Independent Variable A measurement in the

GRAPHING

Variables � � Independent Variable: A measurement in the lab that you have either chosen specifically or have no control over. In chemistry this is usually time or temperature. Dependant Variable: A measurement in the lab that changes when the independent variable changes.

Line Graphs Line graphs are used when data is taken over time.

Line Graphs � You must … �Determine your independent variable and label the x axis (horizontal). �Determine your dependent variable and label the y axis (vertical). �Make sure you use even intervals to number your graph. �Circle and connect the points. �Title your graph: Independent variable versus dependent variable. �Use rulers and pencil.

Interpolation � Interpolation means reading between points. For example, the graph below does not show the exact point for 300 m. L but we can estimate the mass to be 120 g.

Extrapolation � Extrapolation means reading past the graph. For example, the graph below does not show anything higher than 800 m. L but we can estimate at 1000 m. L the mass may be 500 g.

Direct versus Indirect Direct graphs show both the x and y variables increasing at a steady rate.

Direct versus Indirect graphs show one variable increasing while the other is decreasing at a steady rate.

Best Fit Line � When point are given that resemble a line, you may be asked to make a “best fit line” which means use a ruler to find the estimated linear correlation: