Experimental Design Essay examples

Experimental Design Project
Spring 2012

Contents
Question of Interest The Experiment Introduction Response Variable Treatment Factor Blocking Factors Randomization Scheme Experiment Process Expectations Summary of Findings Conclusion Attachment 1: Copy of vocabulary study sheet for test 1 Attachment 2: Copy of vocabulary study sheet for test 2 Attachment 3: Copy of test 1 Attachment 4: Copy of test 2 Page 1 Page 1

Page 3 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8

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Question of Interest
Does studying in a quiet environment with minimal distractions have a different effect on test performance compared to studying in a noisy environment with several distractions?

The Experiment
Introduction: Twenty volunteer students participated in this Latin Rectangle, crossover experiment. The students were asked to study a list of 20 fictitious vocabulary words in a noisy environment with several distractions and complete a matching test in a quiet, controlled testing environment. They were also asked to study a different list of 20 fictitious vocabulary words in a quiet environment with minimal distractions and complete a matching test in the same quiet, controlled testing environment. Response Variable: The response variable was the student’s score on the matching test. There were a total of 20 possible points with no partial credit (possible scores were nonnegative integers, up to 20). Attachments 3 and 4 contain copies of the tests that were given to the students. Treatment Factor:

The treatment factor was the environment students studied in. There were two levels: the noisy environment with several distractions (N) and the quiet environment with minimal distractions (Q). The cafeteria in the Student Union acted as the noisy environment (left picture above). The students were asked to study at a table that was near several other students during lunchtime. The computer lab (A&S 108) was used for the quiet environment (right picture above). Talking, cellphone use, and any other distractions were not permitted during the study time in either environment or during the tests. Blocking Factors: There were two blocking factors in this experiment. The first was a block on the student. The second block was on the version of the test. Since each student took two exams (one in each environment), the same vocabulary words could not be reused, otherwise a carryover effect would likely occur. Therefore, from a pool of 40 fictitious vocabulary words, two tests were created – splitting the 40 words into two groups of 20. Attachment 1 and 2 display the list of vocabulary words and definitions for test version 1 and 2, respectively. These were the handouts given to each student. Randomization Scheme: Students were randomly assigned a combination of treatment level (N or Q) and test version (1 or 2) in such a way that five students participated in each combination. Students fulfilled the requirements of

Page |2 the experiment, then did it once more for the opposite treatment level and test version combination. We aimed to reduce carryover effects of the test taking order through randomization (for example, some students might adopt new studying strategies after experiencing the first exam). Note: the student code below is the first 3 characters of the student’s zipline ID.

Experiment Process: Because of scheduling conflicts, students were split into two groups. The first group participated in the experiment from 12:30 until 1:30. The second group participated in the experiment from 1:30 until 2:30. The experiments were all done on the same Friday afternoon. We almost considered blocking on the time difference; however, the times were so close to each other that we ignored this factor. After observing the different environments at the different times, we confirmed that this factor was not likely to be influential. For each time slot, the students met in the lab, were asked not to talk or use their cell phone for the next

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