One and Two Sample Hypothesis Testing

June 26th, 2009

The 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 »

Program Flow – Using Conditional Statements

June 21st, 2009

The R environment is based on providing access to the R programming language, which like other programming languages has a variety of constructions that can be used to control the flow of the analysis to make various decisions based on testing conditions. For each, in a function for numerical optimisation we might be interested in specifying a tolerance level to determine when the algorithm should stop or a maximum number of iterations. Read the rest of this entry »

Using Histograms to Summarise Data

June 8th, 2009

It 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, 2009

There 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 »

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