SOLUTION: Twenty students randomly assigned to an experimental group receive an instructional program; 30 in a control group do not. After 6 months, both groups are tested on their knowled

Question 467748: Twenty students randomly assigned to an experimental group receive an
instructional program; 30 in a control group do not. After 6 months, both groups
are tested on their knowledge. The experimental group has a mean of 38 on the
test (with an estimated population standard deviation of 3); the control group
has a mean of 35 (with an estimated population standard deviation of 5). Using
the .05 level, what should the experimenter conclude? (a) Use the steps of
hypothesis testing, (b) sketch the distributions involved, and (c) explain your
answer to someone who is familiar with the t test for a single sample but not
with the t test for independent means
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Twenty students randomly assigned to an experimental group receive an
instructional program; 30 in a control group do not.
-------------------------------------
After 6 months, both groups are tested on their knowledge.
The experimental group has a mean of 38 on the test (with an estimated population standard deviation of 3);
---------------
the control group has a mean of 35 (with an estimated population standard deviation of 5).
--------------------
Using the .05 level, what should the experimenter conclude?
(a) Use the steps of hypothesis testing,
Ho: u(c)-u(e) = 0
Ha: u(e)-u(c) > 0 (tests a claim that the instruction helped)
I ran a 2-Sample T test and got the following:
test statistic: t = 2.6482
p-value: 0.0109
Conclusion: Since the p-value is less than 5%, reject Ho.
The test supports the claim.
----------------------------------------------
(b) sketch the distributions involved, and
(c) explain your answer to someone who is familiar with the t test for a single sample but not with the t test for independent means
------
I'll leave b and c to you.
==============================
Cheers,
Stan H.

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