In previous chapters I have examined connections between class size and several classroom processes – within-class groups, teaching and pupil concentration and peer relations. In this chapter I turn to the main statistical analysis and ask whether class size is related to pupils' educational progress. As we saw in Chapter 1 this has been examined in previous research though results are not always clear-cut. We also saw that our study was designed to provide a more sophisticated examination of connections between class size differences and educational progress. It was designed to allow analysis of connections between class size and progress, across the whole range of class size differences, not just comparisons of selected class sizes. It provided an assessment of whether class size effects varied according to the attainments of children, and it controlled for variables that might possibly affect the relationship between class size and attainment. In this chapter we also examine the role that the classroom processes, examined in earlier chapters, have on the connection between class size and children's achievements. This chapter is concerned only with quantitative analyses and includes only those variables entered into quantitative analysis. It does not therefore include qualitative data on classroom processes, reported in earlier chapters. It is also selective in terms of the quantitative process variables it includes. In Chapter 9, results from the quantitative analysis reported in this chapter will be integrated with the qualitative results presented earlier in order to arrive at a full account of the effects of class size.
It is our view that the analyses reported in this chapter are some of the most sophisticated yet undertaken on this topic. However, there is a difficulty when writing a book meant for non-statisticians in that it is not possible or desirable to explain in any detail the statistical approach that has been used or the results. It is important though to understand the basic approach and I shall try to describe this in an accessible way. The interested reader is encouraged to follow up the references below which will provide a