Task 1: Stalking is a very disruptive and upsetting (for the person being stalked) experience in which someone (the stalker) constantly harasses or obsesses about another person. It can take many forms, from being sent intensely disturbing letters threatening to boil your cat if you don’t reciprocate the stalker’s undeniable love for you, to following you around your local area in a desperate attempt to see which CD you buy on a Saturday. A psychologist, who’d had enough of being stalked by people, decided to try two different therapies on different groups of stalkers (25 stalkers in each group – this variable is called Group). To the first group of stalkers he gave what he termed cruel-to-be-kind therapy. This therapy was based on punishment for stalking behaviours: every time the stalkers followed him around, or sent him a letter, the psychologist attacked them with a cattle prod. The second therapy was psychodyshamic therapy, which is a recent development on psychodynamic therapy that acknowledges its limited empirical support (you could say it’s based on Fraudian theory). In keeping with Freud’s ideas the therapist would discuss the stalker’s penis (or lack of it if they were a woman), the penis of their father, their dog’s penis, the penis of the cat down the road and anyone else’s penis that sprang to mind. At the end of therapy, the psychologist measured the number of hours in the week that the stalker spent stalking their prey (stalk2). The therapist believed that the success of therapy might well depend on how bad the problem was to begin with, so had measured the number of hours that the patient spent stalking prior to treatment (stalk1). The data are in the file Stalker.dat.

Analyse the effect of therapy on stalking behaviour after therapy, controlling for the amount of stalking behaviour before therapy. Also try conducting a robust ANCOVA.