When deciding on the research design, one choice is whether to use an experimental or non-experimental design. This depends on the aim of the study. If the aim is to test a prediction that two or more variables are simply associated with each other, the researcher may decide to use a non-experimental or correlational design. However, if the aim is to test a prediction that there is a causal relationship between two variables, then an experimental design is needed. The correlational design examines the relationships between variables as they happen to occur, without altering people’s experiences.The correlational coefficient often is used to measure the association between variables and the results are normally presented graphically in a scatterplot. Sharon aims to find out the link between postnatal depression and the development of mother-infant relationships. Sharon’s research is a non-experimental/correlational study as she doesn’t aim to find out what causes either of the uncontrolled variables (mother’s depression and child’s happiness) but is testing the relationship between them. Sharon plans to summarise the results by presenting the data in a scatterplot correlating the depression scores for each mother with the total ‘happiness’ score for the mother’s child.
To consider whether ‘Sharon’s Study’ is ecologically valid, we need to see if this study can be related to, or reflects everyday, real life. Studies with high ecological validity take place when participants are within their usual surroundings and behaving naturally so that results can be generalised beyond the setting they were carried out in, whereas studies low in ecological validity cannot. Based on this definition, ‘Sharon’s study’ is not ecologically valid due to potential biases related to the opportunity sampling technique, the questionnaire used and the environment of the study not being representative of a natural environment for the infants involved. The sample group in this study is very small and is a poor representation of society. The researcher is using the easiest and most available opportunity sampling technique, risking to produce a biased sample. It consists of mothers and infants that Sharon works with in a local Children’s Centre. Mothers who attend the classes belong to a very specific group and their responses to the questionnaire cannot be generalised to the wider population, unless Sharon specifies that her target population is the mothers with literacy problems. The questionnaire itself represents a source of potential bias as the respondents often tend to provide socially desirable answers to appear in a better light. Mothers in this sample have problems with literacy so credibility of their answers is compromised by possible lack of the question’s comprehension. The researcher intends to analyse the video recordings of herself playing with the children using a time-sampling technique. This creates an artificial situation for the infants as Sharon is not their usual carer and the environment is not as familiar as their own homes would be. In addition to this, time sampling allows for some behaviours to be missed. This may make the observation not representative.
‘Sharon’s study’ is a correlational study where the researcher is measuring two existing and uncontrolled variables: the level of mother’s depression (based on a questionnaire that gives a ‘depression’ score ranging from 0 (no depression) to 30 (high depression) and matches it to a child’s ‘happiness‘ score (calculated by applying a time-sampling technique to analyse video-recordings of Sharon playing with each child). A correlation study looks for a consistent relationship between two variables, such that if a change occurs in one variable, there will be a corresponding change in the other. Variables are thought of as already existing and cannot be manipulated.
The researcher used correlational analysis to test...