Longitudinal Studies

Question 1

example

Answer 1

A longitudinal study is one that follows the same sample over an extended period of time.

Examples:
• National Child Development Study traces the lives of all those born in the same week in March 1958. • Granada TV series ‘7-UP’ which every seven years interviewed a number of children who were seven years old in the early 1960s.

Question 2

advantages

Answer 2

1. Comparative data can be collected. By using fixed response questions in interviews sociologists can make comparisons in changing social attitudes; they can identify trends and changes in attitudes and behaviour.
2. Causes to social divisions can be identified: By studying social groups over long periods of time, it is possible to identify what causes some people to have superior life chances to others in society.
3. Same sample is used: Using the same sample reduces the possibility of a change in responses being due to a different sample being selected at the second or third stage of the study. By using the same sample, one potentially disruptive variable is removed.
4. Tracking large-scale social movements: Longitudinal studies are particularly useful in tracking large-scale patterns of social behaviour such as the relationship between social class and health, education, employment etc.

Question 3

advantages 2

Answer 3

5. Attitude changes over time: The alternative way of tracking attitudes over time is to use oral history. It is much more preferable to ask people about their behaviour at the time rather than years later.
6. Reliability: By using structured questions and asking similar questions at each stage of the study research will be reliable.
7. Representativeness: Often use large sample, carefully selected e.g. all babies born in Britain during a particular week (National Child Development Study).

Question 4

disadvantages

Answer 4

1. ‘Sample attrition’: Keeping in contact with the same sample over a long period of time is a problem - sample members may die, emigrate, opt out etc. A shrinking sample can affect the representativeness of the sample in the later stages of research. If certain groups are more likely than others to be excluded from the sample then the data will become distorted.
2. Maintaining representativeness: The demographic composition of a society may change over time leaving the original sample partially unrepresentative. For example, any sample begun in the 1950s may not include sufficient members of ethnic minority groups to keep the sample representative by the 1970s and 1980s.
3. Changing research interests: The focus of research can change over the whole period of the longitudinal study. For example, there has been more interest in the experiences of the disabled, women and ethnic minority groups in the last twenty years than in the preceding twenty. The result of this kind of problem is that the comparability of data may diminish over time as research concerns change.

Question 5

disadvantages 2

Answer 5

4. Sample membership and their responses: Knowing that they are a member of a sample which is likely to be returned to at regular intervals may affect the responses given. Respondents may become to some extent ‘conditioned’ by their role, giving over-elaborate responses or ones which they feel meet the needs of the research project. Being aware that they are part of an on-going research project may affect the way they respond.
5. Cost: There are relatively few longitudinal studies primarily because of the cost involved in this approach. Researchers have to be highly committed if the work is taking place over a long period of time.
6. Structured research: Longitudinal studies using structured research techniques like structured questions, suffer from the problems associated with them. In particular, the data can be criticised for lacking validity.