According to McBurney and White Essay Example

of a control group. If, however, the self-efficacy measure is used to separate the groups into testing and control group, then the experiment might already be biased. True experiments randomize not just the initially selected group of participants, but also their placements into testing and control groups (Chevalier, 2003; Losh, 2002).

It might be that Rafael has chosen on purpose to assign these groups based on their differences as a method of somehow testing those differences. However, what also makes this a quasi-experiment is the fact that Rafael has made no allowance for the possibility (or rather, the probability) that these children differ according to other variables that have not been made a part of the experiment. Whenever prior information is known about existing differences between the testing and control groups, researchers are expected to put into place statistical controls for these differences (Losh, 2002; Marks, 2006).

For example, some students might have low efficacy for baseball because they have not been exposed enough to it, but be highly interested in playing for a team because they love the game and would like to learn. Yet, these same children might not be able to do this because of prior engagements, lack of parental support, or any number of other reasons. Rafael’s experiment lacks detail on how to deal with these variable aspects of children’s lives.

The lack of any evidence of a treatment protocol in Rafael’s design is a major factor contributing to the classification of this intervention as a quasi-experiment. The lack of protocol will most likely lead to differences in the experience of each of the groups being studied. Not only is it usually desirable in

an experiment that each group follow identical methods of treatment or intervention. Even with a detailed protocol, threats exist in the form of negligence in overseeing the experiment or in the form of subjects who (intentionally or unintentionally) deviate from the procedure.

With no detailed protocol designed for Rafael’s experiment, the dangers of having dissimilar interventions for each group are compounded even further (Chevalier, 2003; Marks, 2006). Another threat to the experimental nature of this intervention regarding the protocol is the necessity that the procedures be representative of the program that Rafael is interested in. That is, whatever procedures make up the protocol should have some amount of resemblance to both baseball and self-efficacy in that activity.

Other considerations such as duration and costs of the experiment also have an effect on their external validity (Chevalier, 2003). With no specified protocol, the external validity of the experiment might be affected. The uncertainty existing in Rafael’s experiment in this regard leads to quasi-experimental status (2003). The size of Rafael’s testing group is also not specified. This poses a problem for more than one reason. Randomization cannot be said to have properly taken place without having a large enough population to choose from (Losh, 2002).

Furthermore, in order to have an internally valid experiment, sample size must be adequate in order to increase the precision of estimates and predictions. Finally, consideration must be given to the possibility that children might drop out of this experiment. Therefore, Rafael needs to specify a large enough sample size for his testing groups so that his experiment might remain valid if some should drop out. Without this specification, the experiment would just be a

quasi-experiment. The main problem with Rafael’s experiment right now is its lack of detail.

The hypothesis is in place, but the design is poorly articulated. Much more thought needs to go into the different aspects of the design, such as inclusion/exclusion criteria, protocol, and sample size. The most glaring problem with this experiment is its apparent lack of proper control and randomization. In the event that differences are known to exist between testing and control groups, it is necessary to build measures into the design that take these variables into consideration. Rafael’s experiment does not appear to address these issues, and therefore must be considered a quasi-experiment.