Many of the concepts we use to describe human behaviour seem to consist of a number of different aspects. Take, for example, the concept of job satisfaction. When we say we are satisfied with our job, this statement may refer to various feelings we have about our work, such as being keen to go to it every day, not looking for other kinds of jobs, being prepared to spend time and effort on it and having a sense of achievement about it. If these different components contribute to our judgement of how satisfied we are with our job, we would expect them to be interrelated. In other words, how eager we are to go to work should be correlated with the feeling of accomplishment we gain from it and so on. Similarly, the concept of job routine may refer to a number of interdependent characteristics such as how repetitive the work is, how much it makes us think about what we are doing, the number of different kinds of tasks we have to carry out each day and so on. Some people may enjoy repetitive work whereas others may prefer a job that is more varied. If this is the case, we would expect job satisfaction to be unrelated to job routine. To determine this, we could ask people to describe their feelings about their job in terms of these characteristics and see to what extent those aspects that reflect satisfaction are correlated with one another and are unrelated to those that represent routine. Characteristics that go together constitute a factor, and factor analysis refers to a number of related statistical techniques that help us to determine them.