In the considered study, there is one independent variable and one dependent variable. The independent variable is the set of instructions that the participants receive, and the dependent variable is the effect on the participant’s sleep (how long it took the participant to fall asleep after taking the pill). The independent variable has two levels, which might be labeled as “sleepy” and “alert”. The “sleepy” level of the independent variable means that the participant was told that the pill would make him or her feel sleepy. The “alert” level of the independent variable means that the participant was told that the pill would make him or her feel awake and alert.
The considered research design is a between-participants design. Indeed, in within-subjects design the participants are exposed to more than one levels of the independent variable, while in between-subjects design the participants are only exposed to one level of the independent variable (Stangor, 2010). In the considered study, each participant received only one set of instructions, either “sleepy” or “alert”. Hence, it is an example of between-subjects design.
If a third condition was added to the present study (the participant receives no information about the pill’s effect), then the number of levels for the independent variable would increase to 3. Since it is not possible to analyze the differences between three variable levels using one t-test, it is necessary to apply ANOVA analysis in this case.
The null hypothesis for ANOVA is the following: participants with any set of pill instructions have same mean value of the time it took them to fall asleep. The alternative hypothesis is the following: the mean value of the time it took the participants to fall asleep is significantly different for at least one independent variable level (Ross, 2010). Hence, if F was significant for such study, it would mean that null hypothesis can be rejected, and that for at least one of the groups (with “sleepy”, “alert” and “no information” levels of the independent variable) the mean value of time needed to fall asleep is significantly different from other groups. In other words, the difference between groups did not emerge due to chance.
References
Ross, S.M. (2010). Introductory Statistics. Burlington, MA: Academic Press.
Stangor, C. (2010). Research Methods for the Behavioral Sciences, 4e, 4th Edition. [VitalSource Bookshelf Online]. Retrieved from http://mbsdirect.vitalsource.com/#/books/1133390072/
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"The terms offer and acceptance." freeessays.club, 17 May 2016
"The terms offer and acceptance." freeessays.club, 17 May 2016
"The terms offer and acceptance." freeessays.club, 17 May 2016
"The terms offer and acceptance." freeessays.club, 17 May 2016