2. Questions to ask about tests scores
1. Do each of these numbers actually conveys
quantitative information?
(scales of measurements)
3. Properties of Scales
MAGNITUDE: the property of “moreness.”
A scale has the property of magnitude if
we can say that a particular instance of the
attribute represents more, less or equal
amounts of the given property than does
the another instance.
4. EQUAL INTERVALS
A scale has the property of equal intervals
if the difference between 2 points at any
place on the scale has the same meaning
as the difference between 2 other points
that differ by the same number of scale
units.
5. ABSOLUTE ZERO
An absolute zero is obtained when nothing
of the property being measured exists.
6. Types of Scales
1. Nominal Scales are really not scales at
all, their only purpose is TO NAME
OBJECTS.
Nominal scales are used when the
information is qualitative rather than
quantitative.
7. 2. A scale with the property of magnitude
but not equal intervals or an absolute 0 is
an ordinal scale.
For most problems in Psychology, the
precision to measure the exact differences
between intervals does not exist. So most
often, one must use ordinal scales of
measurement.
8. 3. When a scale has the properties of
magnitude and equal intervals but not an
absolute 0, it is an interval scale.
9. 4. A scale that has all three properties
(magnitude, equal intervals and absolute
0) is called a ratio scale.
10. 1. Which of the following is least likely to be a variable
among persons in a Testing class?
a) socio-economic status f) speaking ability
b) typing speed g) favorite food
c) nationality h) musical ability
d) assertiveness i) year of birth
e) religious affiliation j) age
2. Which three variables in Question 1 would most likely be
measured in nominal scale?
3. Which option in Question 1 best illustrates an interval but
not a ratio scale?
4. Which two variables in Question 1 are most likely to be
measured by ratio scales?
11. 2. What is the basic pattern of the set of tests
scores? How do they “run”? What do they
“look” like?
(simple ways of tabulating and graphing a
set of scores)
12. What is the basic pattern of the set of
tests scores?
Frequency Distribution: a display that shows
how often each score has occurred.
Grouped Frequency Distribution: a fairly
compact table illustrating how many
people there are in each score interval.
Cumulative Frequency Distributions: how
many people got scores below some
particular values.
13.
14.
15. 3. What is the group like on the average?
In general, have they done as well on the
test as some other groups of examinees?
What is the typical level of performance in
the group?
(middle score statistic to represent the
average or typical score)
16. 1. Mean: the arithmetic average score in a
distribution.
To calculate the mean, we total the scores
and divide the sum by the number of
cases, or N.
17.
18. 4. To decribe the extent to which the scores
spread out away from the average value—
(measures of variability)
19. 5. How does this person stand relative to the
group?
(how a particular individual stands on one
of the tests score)
20. 6. To what extent do those who excel in
Reading also excel in Mathematics? To
what extent do these two abilities go
together in the same individuals?
(correlation)
