**1.
**Suppose that in a study involving only 40 participants,
researchers look at self-esteem differences between two groups. They find a small, but statistically significant,
difference between the self-esteem of the two groups. Based
on this information, would you infer that the measure’s reliability was low or
high? Why?

**Hints: **

·
**The
measure is obviously sensitive. Would a sensitive
measure’s reliability be low or high? **

·
**If,
as the book suggests, random error is like fog, static, and noise, what does
random error due to sensitivity? What is the
relationship between reliability and random error?**

·
**See
pages 199-200. **

2.
List the scales of measurement in
order from least to most accurate and informative.

**Nominal, ordinal, interval, and
ratio.**

3.
Becky wants to know how much
students drink.

·
What level of measurement could
Becky get? Why?

**Hints: Could she measure a true zero? Could she make ratio statements like Jim drinks 2 times as
much as Tom. If so, she should be able to get a
measure that allows her to make ratio statements about how much students drink.
**

·
Becky asks participants: How much
do you drink:

a) drinks; b)
1-3 drinks; c) 3-4 drinks, d) more than 4 drinks. What
scale of measurement does she have?

**Hints: Is there an order to the measure? If so, it is at least ordinal. Are
there equal distances (intervals) between the scores? If
so, it is interval. If not, it is not interval—and cannot
be ratio.**

·
Becky ranks participants
according to how much they drink. What scale of
measurement does she have?

**Hints: If she can order participants from lowest to
highest, she has at least an ordinal scale of measurement. To
do more, she must be able to tell how much of a difference there is between
participants. Can she do that? For
more help, see pages 208-209.**

·
Becky assigns participants a “0”
if they do not drink, a "1" if they are a wine drinker, and a
"2" if they are a beer drinker. What scale of measurement is
this?

**Hints: Does larger number (2) refer to more of a
quality than a (1)? If so, the data are at least
ordinal. If not, do different numbers refer to
different types of drinkers? In that case, what scale
of measurement do you have? For more, see p. 207 **

·
Becky asks participants: How much
do you drink?

1) 0-1 drinks;
2) 1-3 drinks; 3) 3-4 drinks, 4) more than 4, and 5) don't know

**Hints: If she
includes “5” (don't know), is “5” necessarily more than “4” (more than 4 drinks). If she did not have the “5” option, what kind of data
would she have?**

4.
Assume that facial tension is a
measure of thinking.

·
How would you measure facial
tension?

**Facial tension could be measured as the amount of
lines a person gets on his/her face during times of stress or by measuring
electrical activity of facial muscles.**

·
What scale of measurement is it
on? Why?

**You might assume that it is an ordinal scale (more
tension means more thinking). Certainly, it would not
be safe to assume that you had a ratio scale (twice as much tension means twice
as much thinking). Indeed, it would probably not be
safe to assume that you had an interval scale (that there is a perfect
relationship between increases in tension and increases in thinking).**

·
How sensitive do you think this
measure would be? Why?

**The measure of lines on the face might not be
sensitive (there would be a small range of scores and some random observer
error). However, the measure of electrical activity in
the facial muscles might be extremely sensitive. **

5.
Suppose a researcher is
investigating the effectiveness of drug awareness programs.

·
What scale of measurement would
the investigator need if she were trying to discover whether one drug awareness
program was more effective than another?

**Hints: Could nominal scale data show that one group
was more effective than another? What about ordinal
data? **

What scale of
measurement would the investigator need if she were trying to discover whether
one program is better for informing the relatively ignorant than it is for
informing the fairly well-informed?

**Hints: The investigator needs to compare changes in
low scores to changes in high scores. To do that, the
investigator needs to be able to assume that a one-unit change, regardless of
whether it happens to a low score, a medium score, or a high score, represents
the same amount of change. What scale of
measurement is needed to assume that the intervals between numbers are equal?**

6.
In an ideal world, car gas gauges
would be on what scale of measurement? Why?

**Ratio. You would want the
best measurement possible. It would be nice to know
that if you registered having half a tank you really had half a tank.**

In practice,
what is the scale of measurement for most gas gauges? Why
do you say that?

**Ordinal. You know that if
your gauge registers full, it has more gas than if it registers half-full. So, your gas gauge does tell you something about quantity. Therefore, it’s not nominal. However, gas gauges tend to go down slowly
until they register about half-full and then quickly thereafter. That is, it isn’t an equal-interval scale, so it can’t be
interval or ratio.**

7.
Find or invent a measure.

·
Describe the measure.

**Hints: That obviously depends on the measure. To find a measure, you might use one of these links:**

** **http://www.yorku.ca/rokada/psyctest/

http://www.webpages.ttu.edu/areifman/qic.htm

·
Discuss how you could improve its
sensitivity.

**Hints: See green headings on pages 198-203**

·
What kind of data (nominal,
ordinal, interval, or ratio), do you think that measure would produce? Why?

**Hints: See Table 6.3 (p. 216). If
you are still stuck, see Table 6.1 (p.214)**