One of the main strengths of the Trellis graphics paradigm is the use of panelling to divide data into subsets to investigate whether patterns are consistent as the conditioning variables change. In the ggplot2 package the terminology for specifying these separate panels is faceting and can be used to create similar displays. Read the rest of this entry »
Using Faceting in ggplot2 to create Trellis-like Plots
November 9th, 2009Creating scatter plots using ggplot2
November 6th, 2009The ggplot2 package can be used as an alternative to lattice for producing high quality graphics in R. The package provides a framework and hopefully simple interface to producing graphs and is inspired by the grammar of graphics. Read the rest of this entry »
Investigation the relationship between two variables using a scatter plot
October 13th, 2009The relationship between two variables can be visually represented using a scatter plot and will provide some insight into the correlation between the variables and possible models to describe the relationship. There are different ways to produce scatter plots in R making use of either the base graphics system, the lattice graphics library, ggplot2 or other packages. Read the rest of this entry »
Cleveland’s Dot Plots for Plotting Data
September 26th, 2009The dot plot was introduced by Cleveland to provide a powerful visual display to compare groups of data and a function for this type of graphical display is available in the lattice library for R. Data is divided into groups and dots are used to indicate the value of a particular variable with the groups arranged either horizontally or vertically to allow a visual comparison of the distributions for the groups. Read the rest of this entry »
Lattice Graphics Book – Examples Website
September 15th, 2009The author of the lattice graphics library has written a book describing using lattice graphics which provides a large number of examples. A website has been created that shows the graphs using different colour schemes and shows the code that has been used to construct the plots. Read the rest of this entry »
A Gallery of Graphs produced using R
September 12th, 2009The R environment for Statistical Analysis has strong facilities for producing high quality graphical output. There are many books and electronic documents that demonstrate examples of effective ways to display data graphically. To get an feel for the range of display that could be used it is worthwhile visiting the R Graph Gallery. Read the rest of this entry »
Box and Whisker Plots for Summarising Data
August 11th, 2009We have considered using a histogram to summarise univariate data but there are other types of plot such as the box and whisker plot that can be used summarised univariate data. The box and whisker plot is a graphical method for summarising numerical data based on a five-number summary. These five numbers are the minimum, lower quartile, median, upper quartile and maximum value. Read the rest of this entry »
One and Two Sample Hypothesis Testing
June 26th, 2009The t-test is regularly used in Classical Statistics to investigate one or two samples of data and to test a particular hypothesis. There are variants on the t-test that are all handled by the same function, t.test, in R. Read the rest of this entry »
Using Histograms to Summarise Data
June 8th, 2009It is not only possible to use tabular displays to summarise a data set and we will often be interested in using a graphical display as this might be a more effective way to visualise our data rather than using statistics such as the mean or standard deviation. Read the rest of this entry »
Plotting Probability Distributions
June 2nd, 2009There are many distributions that are available within the base R Statistical System and it is possibly to use these functions to visualise the density or cumulative density functions for a distribution with a given set of parameters. Read the rest of this entry »
