Introduction

You are a young analyst. It is Wednesday afternoon and you are fully immersed in an extensive analysis which you have been working on over the evenings to meet the deadline. Suddenly, your phone starts ringing. When you answer it, you hear Professor Novák’s voice:

Prof. Novák: “Hello, I’m having a lecture on Friday and I need a little something from you. I’ve got very simple data from 115 patients with Parkinson’s disease in whom I’ve observed, besides 3 general variables (sex, age, and severity of disease), another 12 parameters (4 parameters related to the patients’ mobility and 8 parameters evaluating CBF, that is cerebral blood flow). What I need from you is to calculate the correlations between the individual parameters from both groups so that I could tell which mobility parameters are related to which parameters of the CBF. It’s going to be the main conclusion of my invited lecture. The organizers count on me to provide the audience with very interesting results, as I always do. I emailed you the data just a few minutes ago. They are excellent, the descriptive summarization has been done by my PhD student who also used the histograms to verify that the data have a normal distribution and are free of any outliers.