Guide to using the learning objectives

1.
Explain^{2
}the advantages of using a multiple group experiment, rather than several
simple experiments, to compare the effectiveness of three or more different
treatments.

2.
Explain^{2
}why a researcher examining the effects of two different treatments might
want to include a no-treatment control group.

3.
Explain^{2
}why using three or more different levels of treatment allows you to
explore the functional relationship between the treatment variable and the
outcome variable. Then, explain^{2} why you would want to explore the
functional relationship between two variables.

4.
Explain^{2
}why multiple-group experiments may have better construct validity than
simple experiments. In your answer, be sure to address hypothesis-guessing,
empty control groups, and confounding variables.

5.
Rank^{6
}the following experiments on the effects of exercise and mood in terms of
how much construct validity you think each would have. Justify^{6} your
rankings.

a.
A 30 min of exercise group and two
control groups: a group that watched music videos and a group that took an
acting class.

b. Two levels of exercise (0 min,
30min)

6.
Rank^{6}the
following experiments on the effects of exercise and mood in terms of how much
construct validity you think each would have. Justify^{6} your
rankings.

a.
Three levels of exercise (0 min, 15 min,
and 30 min)

b. Two levels of exercise (0 min, 30 min)

c.
Four levels of exercise (0 min, 15
min, 30 min, and 45 min)

d. Four levels of exercise (15 min, 30 min,
45 min, and 60 min)

7.
Define^{1
}**within-group variability**. Define^{1} **between-group
variability**. Compare^{4} and contrast^{4 }within-groups variability and
between-groups variability.

8.
Explain^{2
}why, all other things being equal, the greater the variability between
group means, the greater the chance that the treatment had an effect.

9.
Defend^{4
}using the term "error variance" instead of "within-groups variance."

10.
Defend^{4
}the following statement: "It is misleading to call between groups
variance 'treatment variance.'"

11.
Explain^{2
}why you should not use *t*
tests to analyze the results of multiple group experiments.

12.
There
are several terms (all of which end with "variance") for the top part of the F
ratio. Name^{1} those terms.

13.
There
are several terms (all of which end with "variance") for the bottom part of the
F ratio. Name^{1} those terms.

14.
Justify^{2
}the following comment, "if the null hypothesis were true, the *F*
ratio would usually be close to1.0."

15.
Explain^{2
}how to use an *F *table to determine whether an *F* ratio is
statistically significant.

16.
You
have an experiment with 40 participants and four levels of the independent
variable. Calculate^{3}

a.
the degrees of freedom for the
treatment

b. the total degrees of freedom

17.
Describe^{2
}what a statistically significant *F* for the treatment effect
indicates in a multiple-group experiment. State^{1} two important
questions that are **not**
answered by obtaining a significant

18.
Contrast^{4
}post hoc *t* tests with conventional *t* tests. Defend^{4}
the use of post hoc tests for determining which groups' means differ from one
another.

19.
State^{1
}the requirements for conducting a valid post hoc trend analysis and
explain the implications of those requirements on planning a multiple-group
experiment. Then, defend^{4} the use of post hoc test trend analysis.