Most studies of social mobility, such asthe ones described here, have focused upon objective dimensions of mobility that is to say, how much mobility exists, in which directions and for what parts of the population. Gordon Marshall and David Firth 1999 took a different approach in their comparative study of social mobility, investigating people' s subjective feelings about changing class positions. The authors designed their research in response to what they term unsubstantiated speculation among sociologists about the likely effects of social mobility on individuals sense of well-being. While some have argued that social mobility produces a sense of disequilibrium and isolation, others have taken a more optimistic view, suggesting that a gradual process of adaptation to a new class inevitably takes place.