Linear Regressions and Scatterplots

• Categorical (Qualitative) Data: eye color, favorite subject, zip code, favorite animal

• Numerical (Quantitative) Data: Height, weight, number of students in a class

• To determine if data is categorical or numerical, ask if a meaningful average exists.

• Only for numerical/quantitative data

* A graph of a set of data points (x,y)

* A way to determine if 2 variable are related to each other

*Example:

• Think of it in terms of cause and effect: the independent variable (x) causes the dependent variable (y)

• y "depends" on x

• The dependent variable is always graphed on the vertical y-axis and the independent variable is always graphed on the horizontal x-axis

• Extreme values that are either very large or very small with respect to the rest of the data points

Use linear regression to predict the outcome of a progression using a given set of data.

• Click on STAT

• Click on Edit

• Enter the data into L1 and L2

• Click STAT, then right to CALC

• Scroll down to LinReg(ax+b)

• Click Enter, then Enter again

• Click on STAT

• Click on Edit

• Enter the data into L1 and L2

• Click STAT, then right to CALC

• Scroll down to LinReg(ax+b)

• Click Enter, then Enter again