Using statistics to compare instructional programs

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Using statistics to compare instructional programs. Before beginning

a unit on frog anatomy, a seventh-grade biology teacher gives each of the 24 students in the class a pretest to assess their knowledge of frog anatomy. The teacher wants to compare the effectiveness of an instructional program in which students physically dissect frogs with the effectiveness of a different program in which students use computer software that simulates the dissection of a frog. After completing one of the two programs, students will be given a posttest to assess their knowledge of frog anatomy. The teacher will then analyze the changes in the test scores (their score on the posttest minus their score on the pretest).


Suppose the teacher decides to allow the students to select which instructional program on frog anatomy (physical dissection or computer simulation) they prefer to take. Furthermore, suppose that 11 students choose actual dissection and 13 students choose computer simulation.


Here are the results in a test of significance to compare the two groups:


The teacher uses a two sample significance test of means to make a comparison between the two groups. She tests the hypothesis that students who use the computer simulation will see a greater improvement in their scores.
1. Null & Alternate Hypothesis a. Ho: µ1 = µ2 b. Ha: µ1 > µ2 Step 2:
2. Test Statistic: t = 9.27
3. p-value = 0.000
4. Reject Ho. Evidence shows that students who use the computer simulation will see a greater improvement in their scores. In fact, since the p-value is 0, there is strong evidence that this is the case.


Actual Frog Dissection Group difference (posttest-pretest):
Mean 9.1
St Dev 1.04


Computer Simulation Group difference (posttest-pretest):
Mean 27.2 St
Dev 6.95



-Why are her conclusions incorrect?
-Give some examples of flaws in her design and what she could do to improve her study