References : 1- The A-Z of Social Research 2- The Sage Encyclopedia of Qualitative Research Methods Research design /

Classic research design to test whether encouragement from teachers will cause students to do better on IQ tests. The essence of the true experiment is control - the researcher controls everything except the experimental stimulus.

There are a number of factors that can cause experimenters to lose control of their experiments, creating problems of internal and external validity.

Internal validity 1- History The events that happen to the experimental and control group could vary over the course of the experiment. 2- Maturation Biological or psychological processes may become plausible alternative explanations for differences found between the experimental and control groups. 3- Mortality More or different drop-outs in the two groups may cause an artificial difference to emerge. 4- Instrumentation Differences in the measurement procedures applied to the two groups may cause artificial differences to appear. 5- Testing effects This phenomenon is sometimes called `the Hawthorne effect' after a famous series of experiments and observations

External validity There are also three problems that pertain to the external validity of the experiment: The experimental and control groups may not in fact be identical to start with Population validity Artificiality

impossible to control the situation! Most of the social sciences use the experimental method only rarely. The main reason for this is that many of the topics and issues that interest social scientists may not be amenable to experimentation for practical or ethical reasons. It may be impossible to control the situation adequately to allow for experimentation.

Alternative research designs Most research in the social sciences employs research designs other than that of the classical experiment. What kinds of research designs do they rely on instead?

Natural experiments Sometimes chance circumstances will combine in a way that produces a situation that resembles an experimenter generating an experimental and a control group. If researchers realize this and are quick off the mark, they can benefit.

Correlational designs Most researchers, quantitative or qualitative, collect their information or data from the world as is, without any attempt at experimental manipulation. Any research method other than the true experiment, whether it is a survey, a qualitative ethnographic study or whatever, is an example of correlational research.

Correlational research designs Hence, for ethical and practical reasons the only realistic choice of research design for most researchers on most topics is the correlational research design. Correlational research designs do have one crucial advantage over experimental designs that compensates for their lack of control: – correlational designs obtain their data from real people in real situations in the real world. That is, in comparison to experiments, correlational designs are much more validly generalizable to the real world and to the population as a whole.

Definition of Research design Research design refers to the way in which a research idea is transformed into a research project or plan that can then be carried out in practice by a researcher or research team (Sage). Research design is the model used by the researcher to discharge `the burden of proof' - the logical organization that allows him or her to feel that whatever they have done in their research allows them to reach valid conclusions (A-Z).

Definition of Research design The term refers to and encompasses: –decisions about how the research itself is conceptualized. –the subsequent conduct of a specific research project –the type of contribution the research is intended to make to the development of knowledge in a particular area.

Final tips: the key point is that theory does inform the design of all qualitative research, and it is important that this be taken into account and acknowledged in the research design Once the theoretical parameters of the research have been established, other parts of the design can be developed. Research design is much more than simply identifying techniques that will be used to collect data. It involves theoretical, methodological, and ethical considerations that shape both the design and what the research is aiming to achieve.