CH2

Question 1

why we need statistics

Answer 1

1. First, statistics are used for purposes of description.
   –Numbers provide convenient
   summaries and allow us to evaluate some observations relative to others
2. we can use statistics to make inferences,
   –e logical deductions about events that cannot be observed directly

Question 2

exploratory data analysis

Answer 2

the detective work of gathering and displaying clues

Question 3

confirmatory data analysis

Answer 3

when the clues are evaluated against rigid statistical rules

This latter phase
is like the work done by judges and juries.

Question 4

Descriptive statistics

Answer 4

e methods used to provide a concise description of a collection of quantitative information.

Question 5

Inferential statistics

Answer 5

methods used to make inferences
from observations of a small group of people known as a sample to a larger group
of individuals known as a population

Typically, the psychologist wants to make
statements about the larger group but cannot possibly make all the necessary
observations. Instead, he or she observes a relatively small group of subjects (sample)
and uses inferential statistics to estimate the characteristics of the larger group

Question 6

measurement

Answer 6

application of rules for assigning numbers to
objects

The rules are the specific procedures used to transform qualities of attributes into numbers

Question 7

Magnitude

Answer 7

Magnitude is 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 quantity than does another instance

If the coach were to rank the teams by the number of games they have won, then the new numbering system (games won) would have the property of magnitude

Question 8

Equal Intervals

Answer 8

difference between two points at any
place on the scale has the same meaning as the difference between two other points
that differ by the same number of scale units.

When a scale has the property of equal intervals, the relationship between the
measured units and some outcome can be described by a straight line or a linear
equation in the form Y = a +bX

Question 9

Absolute 0

Answer 9

obtained when nothing of the property being measured exists

measuring heart rate and observe that your patient has a rate of 0 and has died, then you would conclude that there is no heart rate at all.

Question 10

Nominal scales

Answer 10

not scales at all;
their only purpose is to name objects. For example, the numbers on the backs of
football players’ uniforms are nominal.

Question 11

ordinal scale

Answer 11

A scale with the property of magnitude but not equal intervals or an absolute 0

rank individuals or objects but not to
say anything about the meaning of the differences between the ranks.

Question 12

interval scale

Answer 12

When a scale has the properties of magnitude and equal intervals but not
absolute 0

most common example of an
interval scale is the measurement of temperature in degrees Fahrenheit.

Question 13

ratio scale

Answer 13

A scale that has all three properties (magnitude, equal intervals, and an absolute 0)

Question 14

distribution of scores

Answer 14

summarizes the scores for a group of individuals. In testing, there are many
ways to record a distribution of scores.

Question 15

frequency distribution

Answer 15

displays scores on a variable or a measure to reflect how frequently each value was obtained

one defines all the possible scores and determines how many people obtained each of those scores..

Question 16

percentile rank

Answer 16

“What percent of the
scores fall below a particular score (Xi)?”

To calculate a percentile rank, you need
only follow these simple steps:
(1) determine how many cases fall below the score of interest,
(2) determine how many cases are in the group, (3) divide the number of cases below the score of interest (Step 1) by the total number of cases in the group (Step 2), and
(4) multiply the result of Step 3 by 100.

Question 17

variance.

Answer 17

average squared deviation around the mean,

where (X - Xbar) is the deviation of a score from the mean.

Question 18

standard deviation

Answer 18

square root of the average squared deviation around the mean.

Question 19

knowing the standard deviation of a normally distributed batch of data allows us to

Answer 19

make precise statements about the
distribution.

Question 20

One problem with means and standard deviations

Answer 20

do not convey enough information for us to make meaningful assessments or accurate interpretations of data

Question 21

Z score

Answer 21

transforms data into standardized units that are easier to interpret. A Z score is the difference between a score and the mean, divided by the standard deviation

Question 22

Any variable transformed into Z score units takes on special properties

Answer 22

Z scores have a mean of 0 and a standard deviation of 1.0.

Question 23

McCall’s T

Answer 23

mean of the distribution would be set at 50 to correspond with the 50th percentile. standard deviation was set at 10.

T = 10z + 50

Question 24

stanine system

Answer 24

Another system developed in the U.S. Air Force during World War II

converts any set of scores into a transformed
scale, which ranges from 1 to 9.

Question 25

Norms

Answer 25

performances by defined groups on particular tests

The norms for a test are based on the
distribution of scores obtained by some defined sample of individual

Question 26

When applying an IQ test, the tester’s task is to determine

Answer 26

the mental age of the person being tested. This is accomplished through various exercises that help locate the age-level norm at which a child is performing.

Question 27

tracking

Answer 27

This tendency to stay at about the same level relative to one’s peers

Question 28

norm-referenced test

Answer 28

compares each person with a norm

Many critics have objected that this use of tests forces competition among people.
Young children exposed to many norm-referenced tests in elementary school can
get caught up in a never-ending battle to perform better than average

Question 29

criterion-referenced test

Answer 29

describes the specific types of skills, tasks, or
knowledge that the test taker can demonstrate such as mathematical skills

tests that are applied to determine whether students know specific information. These tests
do not compare students with one another; they compare each student’s performance with a criterion or an expected level of performance