How to calculate least squares fit in Excel

Least Squares Fit is a statistical method that is used to find the line of best fit for a set of data points. The line of best fit is a line that is closest to all the data points and is used to predict the value of a dependent variable based on the value of an independent variable. In Microsoft Excel, you can calculate a Least Squares Fit using the LINEST function.

Here’s how to calculate a Least Squares Fit in Excel:

Prepare your data

Before using the LINEST function, make sure that your data is organized into a clear and consistent structure. You’ll need two columns of data: one for the independent variable and one for the dependent variable.

Enter the LINEST function

To enter the LINEST function, follow these steps:

  • Select the cell where you want to display the result of the calculation.
  • Type the following formula: =LINEST(dependent_variable, independent_variable, TRUE, TRUE).
  • Replace “dependent_variable” with the range of cells that contain the dependent variable data.
  • Replace “independent_variable” with the range of cells that contain the independent variable data.

After typing the formula, instead of pressing the Enter key directly, if you’re entering an array formula, press Ctrl+Shift+Enter. This action tells Excel that you’re entering an array formula, which allows the LINEST function to return multiple values.

Excel will then display the formula enclosed in curly braces {} to indicate it’s an array formula. The first value is the slope of the line of best fit, and the second value is the y-intercept.

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Note: The TRUE argument in the LINEST function specifies that the function should return additional statistical information, such as the standard error and the R-squared value.