Generally, in market research surveys, marketing managers would have some hypothesis that they would like to test out? In a survey for a cigarette brand, for example, one hypothesis maybe : “Female smokers generally prefer lower nicotine concentrations in cigarettes”. These hypothesis are generally around demographic differences in behavior, attitudes and lifestyle choices. Or they could be generated by “folk knowledge” about the market as in the example above. They could also be differences around the strength of brands or products along different parameters.
Very often hypothesis are not framed explicitly – for example, when comparing two potential advertisements on “credibility” post exposure. In these cases, either advertisement may fare better than the other and we may not have prior knowledge about this difference. Statistical procedures for comparison remain the same.
In all such analysis, significance testing of differences in proportions or means are used to compare differences. More than two groups may be compared over multiple variables. For testing of differences in mean effects of some treatment (say exposure to an advertisement) for different groups (say different SEC groups), a procedure called ANOVA is used where overall difference is first gauged before undertaking group-wise comparisons.