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Finding Residuals and Creating Residual Plots - Excel quiz

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  • What is a residual in regression analysis?
    A residual is the difference between the actual observed value and the predicted value from the regression line.
  • What is the regression line equation used in the example?
    The regression line equation used is y = -1.04x + 79.1.
  • What is the first step in creating a residual plot in Excel?
    The first step is to create a scatter plot of the original data.
  • How do you display the regression equation on an Excel scatter plot?
    You add a trend line to the scatter plot and check the option to display the equation on the chart.
  • How do you calculate predicted values (y hat) using the regression equation in Excel?
    Plug each x value into the regression equation to compute the predicted y (y hat) for each data point.
  • What formula is used to calculate residuals in Excel?
    Residuals are calculated as actual y minus predicted y (y hat).
  • Why should residuals be placed next to the x data in Excel?
    Residuals should be next to the x data so you can easily create a residual plot by selecting both columns.
  • What type of chart is used to create a residual plot in Excel?
    A scatter plot is used to create a residual plot.
  • What does a random scatter of residuals around zero indicate about the model fit?
    A random scatter of residuals around zero suggests that the linear model is a good fit for the data.
  • How can you copy formulas for predicted values and residuals across multiple cells in Excel?
    You can click and drag the solid black cross at the bottom right corner of the cell to copy the formula across the table.
  • What should you title your residual plot in Excel to avoid confusion?
    You should title it 'Residual Plot' to distinguish it from the original scatter plot.
  • Where is it helpful to place the residual plot relative to the original scatter plot?
    It is helpful to place the residual plot below the original scatter plot to compare them easily.
  • What does it mean if residuals are both positive and negative and close to zero?
    It means the model predicts well, as errors are small and distributed on both sides of the regression line.
  • What is the purpose of creating a residual plot?
    The purpose is to assess the fit of the regression model and check for patterns in the residuals.
  • What should you do if you want more practice creating residual plots in Excel?
    You should check out the examples and practice exercises provided in the lesson.