The 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 »
Investigation the relationship between two variables using a scatter plot
October 13th, 2009Cleveland’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 »
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 »
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 »
Cross-tabulation of Data
May 15th, 2009The contingency table is used to summarise data when there are factors in the data set and we are interested in counting the number of occurrences of each combination of factor variables. In R there are different ways that these types of table can be produced and manipulated as required. Read the rest of this entry »
Producing Data Summaries
May 11th, 2009The first stage of most investigations is to produce summaries of the data to identify any unusual records and to get a overall feel for the contents of the data. This initial data analysis usually involves tabulation and plotting of data and there are a variety of functions available in R to generate the required summaries of interest. Read the rest of this entry »
