Having successfully slayed audiences at holiday camps around the country, my next step towards global domination was my primary school. I had learnt another Chuck Berry song ('Johnny B. Goode'), but also broadened my repertoire to include songs by other artists (I have a feeling 'Over the edge' by Status Quo was one of them).¹ Needless to say, when the opportunity came to play at a school assembly I jumped at it. The headmaster tried to have me banned,² but the show went on. It was a huge success (I want to reiterate my earlier point that 10-year-olds are very easily impressed). My classmates carried me around the playground on their shoulders. I was a hero. Around this time I had a childhood sweetheart called Clair Sparks. Actually, we had been sweethearts since before my newfound rock legend status. I don't think the guitar playing and singing impressed her much, but she rode a motorbike (really, a little child's one) which impressed me quite a lot; I was utterly convinced that we would one day get married and live happily ever after. I was utterly convinced, that is, until she ran off with Simon Hudson. Being 10, she probably literally did run off with him - across the playground. I remember telling my parents and them asking me how I felt about it. I told them I was being philosophical about it. I probably didn't know what philosophical meant at the age of 10, but I knew that it was the sort of thing you said if you were pretending not to be bothered about being dumped.

If I hadn't been philosophical, I might have wanted to look at what had lowered Clair's relationship satisfaction. We've seen in previous chapters that we could predict things like relationship satisfaction using regression. Perhaps it's predicted from your partner's love of rock bands like Status Quo (I don't recall Clair liking that sort of thing). However, life is usually more complicated than this; for example, your partner's love of rock music probably depends on your own love of rock music. For example, if you both like rock music then your love of the same music might have an additive effect, giving you huge relationship satisfaction (moderation), or perhaps the relationship between your partner's love of rock and your own relationship satisfaction can be explained by your own music tastes (mediation). In the previous chapter we also saw that regression could be done with a dichotomous predictor (e.g., rock fan or not) but what if you wanted to categorize musical taste into several categories (rock, hip-hop, R & B etc.)? Surely you can't use multiple categories as a predictor in regression? This chapter extends what we know about regression to these more complicated scenarios. First we look at two common regression-based models - moderation and mediation - before expanding what we already know about categorical predictors.

¹ This would have been about 1982, so just before they became the most laughably bad band on the planet. Some would argue that they were always the most laughably bad band on the planet, but they were the first band that I called my favourite band.

² Seriously! Can you imagine a headmaster banning a 10-year-old from assembly? By this time I had an electric guitar and he used to play hymns on an acoustic guitar; I can assume only that he somehow lost all perspective on the situation and decided that a 10-year-old blasting out some Quo in a squeaky little voice was subversive or something.