Factorial Designs: A Visual
Approach
No numbers!
Research design explained
• This tutorial is based on the example
study described on page 420 of
Research designed explained.
• This tutorial is based on the example study
described on page 420 of Research
designed explained.
• In that study, all participants read 60
statements aloud. These statements
were presented as a Powerpoint slide
show.
• This tutorial is based on the example study
described on page 420 of your text.
• In that study, all participants read 60
statements aloud. These statements were
presented as a Powerpoint slide show.
• However, not all slide shows were the
same.
• This tutorial is based on the example study described on
page 420.
• In that study, all participants read 60 statements aloud.
These statements were presented as a Powerpoint slide
show.
• However, not all slide shows were the same.
• Some slide shows presented negative statements
(e.g., “I feel a little low today”), whereas other slide
shows presented positive statements (e.g., “I feel
pretty good today”). Thus, some participants read
positive statements, whereas others read negative
statements.
• This tutorial is based on the example study described on
page 420.
• In that study, all participants read 60 statements aloud.
These statements were presented as a Powerpoint slide
show.
• However, not all participants read the same 60
statements. Some read positive statements (e.g., “I feel
pretty good today, though”), whereas others read
negative statements (e.g., “However, I feel a little low
today”).
• In addition, the slide shows varied in how
fast they presented the statements. Some
slide shows presented the statements at a
fast rate; others presented the statements at
a slow rate. Thus, some participants had to
read and say the statements at a fast pace;
the other participants did so at a slow pace.
Visually, we can diagram the
design as follows:
Participants
Negative statements
Slow
Fast
Positive statements
Slow
Fast
•
In short, participants saw one of four
slide shows:
1.
2.
3.
4.
Slow paced, negative statements show
Fast paced, negative statements show
Slow paced, positive statements show
Fast paced, positive statements show
•
Thus, the experimenters varied two
things:
1. Pace of the slide show (slow or fast) and
2. Type of statement (negative or positive)
• For the purpose of this tutorial, imagine
that participants rated their mood on the
following scale.
Unhappy
Happy
• Thus, a darker color represents a darker
mood, and a lighter color represents a
lighter mood.
Unhappy
Happy
Interactions
• As you can see from the next slide, this
scale allows us to average participants
responses without using numbers.
Unhappy
Happy
Color 1
Color 2
(Black)
(Black)
(Gray)
(Gray)
(White)
(Black)
(White)
(White)
Average of
Colors 1 & 2
(Black)
(Gray)
(White)
(Gray)
• Now, let’s look at some possible results.
• Now, let’s look at some possible results.
• Let’s start with the manipulations having
no effect.
Suppose we observed no effect for any of the slide
shows: Regardless of condition, everyone ended up in a
good (light) mood.
Slow speed Fast speed
Negative
Statements
Positive
statements
Because type of statement does not matter, we
could combine the results from the negative and
positive statements, like this:
Slow speed
Negative
statements and
positive
statements
Fast speed
Alternatively, because presentation speed does
not matter, we could combine (collapse) the results
from the slow and fast statements, like this:
Slow and fast
presentations
Negative statements
Positive statements
Finally, because neither presentation speed nor
statement type matter, we could combine
(collapse) the results into one box, like this:
Slow and fast
presentations
Negative statements
and positive statements
Suppose we observed no effect for any of the slide
shows: Regardless of condition, everyone ended up in a
bad (dark) mood.
Slow speed Fast speed
Negative
Statements
Positive
statements
Because type of statement does not matter, we
could combine (collapse) the results from the
negative and positive statements, like this:
Slow speed
Negative
statements and
positive
statements
Fast speed
Alternatively, because presentation speed does
not matter, we could collapse the results from the
slow and fast statements, like this:
Slow and fast
presentations
Negative statements
Positive statements
Finally, because neither presentation speed nor
statement type matter, we could combine
(collapse) the results into one box, like this:
Slow and fast
presentations
Negative statements
and positive statements
Suppose we observed no effect for any of the slide
shows: Regardless of condition, everyone ended up in a
neutral (gray) mood.
Slow speed Fast speed
Negative
Statements
Positive
statements
Because type of statement does not matter, we
could collapse the results from the negative and
positive statements, like this:
Slow speed
Negative and
positive
statements
Fast speed
Alternatively, because presentation speed does
not matter, we could collapse the results from the
slow and fast statements, like this:
Slow and fast
presentations
Negative statements
Positive statements
Finally, because neither presentation speed nor
statement type matter, we could combine
(collapse) the results into one box, like this:
Slow and fast
presentations
Negative and
positive statements
• In the next 4 slides, let’s look at the case
in which positive statements help mood
more than negative statements.
• This would be called a “statement main
effect.”
Suppose the only effect was that positive statements had
a more positive effect on mood than negative statements.
(Slide 1 of 4)
Slow and Fast Presentations
Negative Statements
Positive Statements
Suppose positive statements have a more positive
effect on mood than negative statements
(Slide 2 of 4)
Slow speed Fast speed
Negative
Statements
Positive
statements
Suppose positive statements have a more positive
effect on mood than negative statements
(Slide 3 of 4)
Slow speed Fast speed Statement
Averages
Negative
Statements
Positive
statements
On average, participants getting
negative statements are in a
darker mood than those getting
positive statements, suggesting
an effect for statement type.
Negative
Positive
Suppose positive statements have a more positive effect
on mood than negative statements(Slide 4 of 4)
Slow speed Fast speed Statement
Averages
Negative
Statements
Negative
Positive
Positive
statements
On average, participants getting the slow slide show are in the
same mood than as getting the fast show, suggesting
no effect for speed of presentation.
Speed
Averages
Slow
Fast
• In the next 4 slides, let’s look at the case
in which fast presentation of statements
boosts mood more than slow presentation
of statements.
• This would be called a “presentation
speed main effect.”
Statements presented quickly seem to boost mood more
than statements presented slowly (Slide 1 of 4)
Slow speed
Speed has
the same
effect for
Positive
both
Statements
positive and
negative
statements
Negative
Statements
Fast speed
Statements presented quickly seem to boost
mood more than statements presented slowly
(Slide 2 of 4)
Slow speed Fast speed
Negative
Statements
Positive
statements
Statements presented quickly seem to boost mood
more than statements presented slowly (Slide 3 of 4)
Slow speed
Fast speed
Negative
Statements
Positive
statements
On average, participants getting the slow slide show are in the
darker mood than those getting the fast show, suggesting
an effect for speed of presentation.
Average of
slow and fast
speeds
Slow
Fast
Statements presented quickly seem to boost mood
more than statements presented slowly (Slide 4 of 4)
Slow speed
Fast speed
Negative
Statements
Positive
statements
Negative
Same
Average of
slow and fast
speeds
Average for
negative and
positive
statements
Positive
Slow
Different
Fast
• Now, let’s look at some interactions. In an
interaction, a treatment’s effect in one
condition is different from its effect in
another condition.
• Sometimes, interactions occur because a
treatment has one effect in one condition,
but the opposite effect in another
condition. For example, some medications
can have positive effects under certain
circumstances, but negative effects under
others.
Interaction:
Slow speed Fast speed
Negative
Statements
Positive
statements
Mood lightens (+)
Mood darkens (-)
Speeding up the pace
improves mood in the negative statements condition,
but worsens mood in the positive statements condition.
Interaction:
Slow speed Fast speed
Negative
Statements
Positive
statements
Mood darkens (-)
Mood lightens (+)
Speeding up the pace
worsens mood in the negative statements condition,
but improves mood in the positive statements condition.
• Sometimes, interactions occur because a
treatment has an effect in one condition,
but no effect in another condition.
Interaction:
Slow speed Fast speed
Negative
Statements
Positive
statements
Mood does not change (0)
Mood lightens (+)
Speeding up the pace has no effect on mood
in the negative statements condition,
but improves mood in the positive statements condition.
Interaction:
Slow speed Fast speed
Negative
Statements
Positive
statements
Mood lightens (+)
Mood does not change (0)
Speeding up the pace has no effect on mood
in the negative statements condition,
but improves mood in the positive statements condition.
Interaction:
Slow speed Fast speed
Negative
Statements
Positive
statements
Mood darkens (-)
Mood does not change (0)
Speeding up the pace has darkens mood
in the negative statements condition,
but has no effect on mood in the positive statements
condition.
Interaction:
Slow speed Fast speed
Negative
Statements
Positive
statements
Mood darkens (-)
Mood does not change (0)
Speeding up the pace has darkens mood
in the negative statements condition,
but has no effect on mood in the positive statements
condition.
• Sometimes, interactions occur because a
treatment has more of an effect in one
condition than in another.
Interaction:
Slow speed Fast speed
Negative
Statements
Positive
statements
Mood lightens slightly (+)
Mood lightens greatly (++)
Speeding up the pace has lightens mood slightly
in the negative statements condition,
but lightens mood considerably in the
positive statements condition.
Interaction:
Slow speed Fast speed
Negative
Statements
Positive
statements
Mood darkens greatly (--)
Mood darkens slightly (-)
Speeding up the pace has darkens mood greatly
in the negative statements condition,
but darkens mood slightly in the
positive statements condition.
END