R Programming Tutorial for Linear Regression

Fitting of Simple Linear Regression

Load the data into R. The procedure for loading of data files has been shown in previous R tutorials. Here, we use a data set from a pre-installed package “fma”.

Loading Data set from a Package in R

{`
  To load data from the package in R, use the commands:
  >data (package=”fma”)
  This instantly presents a list of all data sets available within the package.

  Now, to load the data set “advert”, use the command:
  >data(advert)

  Now print the data in R by:
  >advert`}
  

How to Use R software for carrying out Linear Regression Analysis?

To fit the data into a simple linear regression model using R programming we use the following commands:

{`
  Define a variable name (here, model) and use the command:
  >model <- lm (sals~advert, data=advert)

  To view the intercept and slope of regression in R, print 
  > model`}
  

{`To print the entire summary of the regression using R software, use the command:
  >summary (model)`}
  

{`The following command can be used to find the residuals of individual observations:
  >residuals (model)`}
  

How to Draw a Scatter Plot using R?

{`To draw a scatter plot between sales and advert we use the following command:
  >plot (sales~advert, data= advert, main=” Sales and Advertising expenditure”, xlab=” Advertising expenditure”, ylab=” sales”)
  `}

main is used to define the title of the scatterplot while xlab and ylab are used to set X-axis and Y-axis labels.

How to display the Line of best Fit in Linear Regression scatter plot in R?

{`Display line of best fit by using the following the command:
  >abline(model)`}

How to use R programming software for Data FORECAST?

{`Forecast data when adverting expenditure is 30. Use the following command:
  >predict(model, newdata=data.frame(advert=30))
  `}

Sample Assignment on Linear Regression Modelling in R

Learn R programming for Statistical Analysis

• Introduction to R programming
• How to Load Data set in R
• Linear Regression Modelling in R program
• Time series Analysis using R program
• Time series Forecasting and Decomposition using R
• Forecasting Linear Trend using R