One way, two way and n way ANOVA are used to test difference in means when we have one, two and n factor variables. A key assumption when performing these ANOVAs is that the measurements are independent. When we have repeated measures this assumption is violated, so we have to use repeated measures ANOVA. Repeated […]

# statistics

## Nonparametric Tests Exercises

In this set of exercises you will be presented with real-life problems in marketing. Your task will be to choose appropriate nonparametric statistical technique and solve the problem using appropriate R functions. Answers to the exercises are available here. Exercise 1 A company wants to learn if sales income is equaly distributed among the stores. […]

## Two Way ANOVA in R Exercises

One way analysis of variance helps us understand the relationship between one continuous dependent variable and one categorical independent variable. When we have one continuous dependent variable and more than one independent categorical variable we cannot use one way ANOVA. When we have two independent categorical variable we need to use two way ANOVA. When […]

## Network Analysis Part 2 Exercises

In this set of exercises we shall practice the functions for network statistics, using package igraph.If you don’t have package already installed, install it using the following code: install.packages(“igraph”) and load it into the session using the following code: library(“igraph”) before proceeding. You can find more info about the package and graphs in general here […]

## One Way Analysis of Variance Exercises

When we are interested in finding if there is a statistical difference in the mean of two groups we use the t test. When we have more than two groups we cannot use the t test, instead we have to use analysis of variance (ANOVA). In one way ANOVA we have one continuous dependent variable […]

## Paired t-test in R Exercises

The paired samples t test is used to check if there are any differences in the mean of the same sample at two different time points. For example a medical researcher collects data on the same patients before and after a therapy. A paired t test will show if the therapy improves patient outcomes. There […]

## Network Analysis Part 1 Exercises

In this set of exercises we shall create an empty graph and practice the functions for basic manipulation with vertices and edges, using the package igraph. If you don’t have the package already installed, install it using the following code: install.packages(“igraph”) and load it into the session using the following code: library(“igraph”) before proceeding. You […]

## Independent t test in R

The independent t test is used to test if there is any statistically significant difference between two means. Use of an independent t test requires several assumptions to be satisfied. The assumptions are listed below The variables are continuous and independent The variables are normally distributed The variances in each group are equal When these […]

## Examining Data Exercises

One of the first steps of data analysis is the descriptive analysis; this helps to understand how the data is distributed and provides important information for further steps. This set of exercises will include functions useful for one variable descriptive analysis, including graphs. Before proceeding, it might be helpful to look over the help pages […]