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How to Complete a Regression Analysis in Minitab 18
Why We Use Regression Analysis
When you look at a scattered plot graph created from the plotting of dots from two different axes, you may find that the variables are inversely related directly related to each other. If the line you draw to estimate regression and the data is seems to be moving from left to right and moving upward the data is said to be directly related and vise versa if inversely related. Its nice to have a quick view of the scattered plot, but our line can be more accurately drawn through regression analysis. In this tutorial will we create a scattered plot with a regression line and also create residual plots for the dependent variable.To follow along download this Minitab file. Also, if you don't have the latest version of mini tab you can download a trial for the new version here.
Add Data to Minitab
To add data it must entered or pasted in from Excel. The data should com in the form of X,Y separately to be able to complete an analysis.
Set-up Scattered Plot With Regression
The first graph that we need to bring up for a regression analysis is a scattered plot graft. To set-up this graph click Graph→Scatterplot. When the scatterplot window appears select the box labeled "With Regression" and click OK. When the scattered plot with regression window appears put the cursor in the first row of the Y-axis box, then double click on the Y variable to the left. Next, double click on the X variable and it will populate the X section. A default name will appear if you do not create a title so I'm going to create my own title by clicking on "Labels." Then click in the title text box and type "Scatter Plot Graph of Cars Sold VS. TV Ads" and click OK. Click the OK button again and the scatter plot diagram with regression will appear.
Click the Tab Graph and Select Scattered Plot
Select With Regression
Set-up Fit Regression Model
To set-up additional regression graphs click Data→Regression→Regression→Fit Regression Model. Now you must place your cursor in the "Responses" section and click on the cars sold header (Y variable) to the left. Click in the "Continuous predictors" section and then click on TV Ads header (X variable). Find the storage button and click on it. From the check boxes select Fits, Standardized residuals, and Coefficients. Click Okay. There one more task that will allow us to show multiple residual graphs. Click on Regression Graphs and choose the option "Four in one." Now click Okay. Then click OK again.
Click Data, Regression, Regression, Fit Regression Model
Scattered Plot, Residual Plots, and Regression Output Data
The scattered plot show us that the amount of cars sold is directly related to the amount of TV adverting. We could have visibly found this true without having the regression display in our graph. The residual plots show graphically difference between the observed value of the dependent variable (y) and the predicted value (x). And finally the output data shows a numerical analysis of the variance.
Boyer, K. & Verma, R. (2010). Operations & supply chain management for the 21st century. Mason, OH: South-Western.
© 2018 Joshua Crowder