The next step,the research design,addresses how to implement the strategy determining a research design requires about three basic aspects of the research study :
1. Group versus individual. Will the study examine a group of individuals, producing an overall description for the entire group,or should the study focus on a single individual ? Although group studies tend to have higher external validity ,the careful examination of a single individuals often can provide detail that is lost in averaging a large group.
2. Same in individual versus different independents.Some research examines change within the same group of individuals as they move from one treatment to the next. Other research uses a different group of individual for each separate treatment and then examines differences between groups. Each design has advantage and disadvantages that must be weighed in the planning phase.
3. The number of variable to be included . The simplest study involves examining the relationship between two variables.However, some research involves three or more variables.For example,a research may be interested in multiple relationships, or a study may focus on two variables but ask how their relationship is affected by other variables.Thus,one factor in determining a research design is deciding how may variables will be observed,manipulated,or regulated.