W3 - Chapter 3 - DN Flashcards
1
Q
arithmetic mean
A
- a measure of central tendency
- derived by calculating an average of all scores in a distribution
- also called the mean
p. 89
2
Q
average deviation
A
- a measure of variability
- derived by
- summing the absolute value of all the scores in a distribution and
- dividing by the total number of scores
p. 94
3
Q
bar graph
A
- a graphic illustration of data
- numbers indicative of frequency are set on the vertical axis
- categories are set on the horizontal axis
- the rectangle bars that describe the data are typically noncontigous
p. 85
4
Q
bimodal distribution
A
- a distribution where the central tendency consists of
- two scores
- occurring an equal number of times
- and are the most frequently occurring scores in the distribution
p. 91
5
Q
bivariate distribution
A
- a graphic representation of correlation
- accomplished by the simple graphing of the coordinate points for values of
- the X-variable and
- the Y-variable
- also known as a
- scatterplot
- scatter diagram
- scattergram
p. 111
6
Q
coefficient of correlation
A
- symbolised by **r **
- the correlation coefficient is an index of the strength of the linear relationship between two continous variables
- expressed as a number
- can range from -1 to +1
- most frequently used statistic to calculate is the Pearson r
p. 106
7
Q
coefficient of determination
A
- a value indicating how much variance is shared by two variables
- this value is obtained by
- squaring the obtained correlation coefficient
- multiplying by 100 and
- expressing the result as a percentage
- this indicates the amount of variance accounted for by the correlation coefficient
- i.e., “total variance explained”
p.109
8
Q
correlation
A
- an expression of the degree and direction of relationship (correspondence) between two variables
- where each variable is continuous in nature
p. 106-116
9
Q
curvilinearity
A
- the degree to which a graph or scatterplot is characterized by curvature
p. 111
10
Q
distribution
A
- in a psychometric context
- a set of test scores arrayed for recording or study
p.83
11
Q
dynamometer
A
- an instrument used to measure the strength of hand grip
p. 82
12
Q
effect size
A
- a statistic used to express
- the strength of a relationship or
- the **magnitude **of the differences in data
- in meta-analysis - this statistic is most typically a correlation coefficient
p. 115
13
Q
error
A
- all of the factors (other than what a test purports to measure) that contribute to scores on a test
- error is a variable that exists on all testing and assessment
p. 78-79
14
Q
frequency distribution
A
- a tabular listing of
- scores
- along with the number of times each score occurred
p.83-85
15
Q
frequency polygon
A
- a graphic illustration of data
- frequency numbers set on the vertical axis
- test scores or categories are set on the horizontal axis
- data is described by a continous line connecting all of the points where the test scores or categories meet frequencies
p. 85,86
16
Q
graph
A
- a diagram or chart
- composed of lines, points, bars, or other symbols that describe and illustrate data
p.85
17
Q
grouped frequency distribution
A
- a tabular summary of test scores
- the test scores are grouped by intervals
- also referred to as class intervals
p. 84-85
18
Q
histogram
A
- a graph with vertical lines drawn at the true limits of each test score (or class interval)
- these lines form a contigous rectangle
p. 85,86
19
Q
interquartile range
A
- an ordinal statistic of variability
- equal to the difference between the third & first quartile points in a distribution that has been divided into quartiles
p. 94
20
Q
interval scale
A
- a system of measurement
- all items are rank-ordered into equal intervals
- every unit on the scale is equal to every other
- there is no absolute zero point
- this precludes mathematical operations on the data
p.81
21
Q
kurtosis
A
- an indication of the nature of the steepness of the centre of the distribution
- i.e., peaked vs flat
p.97-98
22
Q
leptokurtic
A
- a description of the kurtosis of a distribution that is relatively peaked at its centre
23
Q
linear transformation
A
- in psychometrics
- a process of changing a score such that
- the new score has a direct numerical relationship to the original score
- the magnitude of the difference between the new score & other scores on the scale parallels the magnitude of differences on the scale from which it was derived
- contrast with nonlinear transformation
p. 104
24
Q
mean
A
- a measure of central tendency
- derived by calculating an average of all scores in a distribution
- also called an arithmetic mean
p. 89
25
Q
measurement
A
-
assigning numbers or symbols to characteristics of people or objects
- according to rules
p.78-79
26
Q
measure of central tendency
A
- one of three statistics indicating the average or middlemost score between the extreme scores in a distribution
- mean - ratio level
- median - ordinal (takes the order of scores into account)
- mode - nominal
p.89
27
Q
measure of variability
A
- a statistic indicating how scores in a distribution are scattered or dispersed
- common measures of variability are
- range
- standard deviation
- variance
p.92
28
Q
median
A
- a measure of central tendency
- derived by identifying the middlemost score in a distribution
p. 89-91
29
Q
mesokurtic
A
- a description of the kurtosis of a distribution
- that is neither extremely peaked nor flat in its centre
p.97
30
Q
meta-analysis
A
- a family of techniques
- used to statistically combine information across studies
- to produce single estimates of the statistics being studied
p. 115
31
Q
mode
A
- a measureof central tendency
- derived by identifying the most frequently occurring score in a distribution
p. 89, 91-92
32
Q
negative skew
A
- when relatively few scores fall at the lower end of the distribution
- negatively skewed exmination results may indicate the test was too easy
- some more difficult questions would better discriminate between scores at the higher end
p.97
33
Q
nominal scale
A
- a system of measurement
- all things being measured are classified or categorised, based on one or more distinguishing characteristics
- placed into mutually exclusive & exhaustive categories
p. 79-80
34
Q
nonlinear transformation
A
- in psychometrics
- a process of changing a score such that
- the new score does not necessarily have a direct numerical relationship to the original score, and
- the magnitude of the diffferences between the new score & the other scores on the scale, may not necessarily parallel the magnitude of differences of those from the original scale
- contrast with linear transformation
p. 104
35
Q
normal curve
A
- bell-shaped, smooth, mathematically defined curve
- highest at the centre & gradually tapered on both sides - approaching but never touching the horizontal axis
p. 85, 87, 98
36
Q
normalized standard score scale
A
- conceptually, the end product of “stretching” a skewed distribution into the shape of a normal curve
- usually through a non-linear transformation
p. 104-106
37
Q
normalizing a distribution
A
- a statistical correction applied to distributions meeting certain criteria
- for the purpose of approximating a normal distribution
- thus making the data more readily comprehensible or manipulable
p.104
38
Q
ordinal scale
A
- a system of measurement , where all things being measured can be rank-ordered
- the rank-ordering implies nothing about how much greater one ranking is than another
- no absolute zero point on the scale
- most scales in psychology & education are ordinal
p. 80-81
39
Q
outlier
A
- an extremely atypical plot point in a scatterplot
- any extremely atypical finding in research
p.111
40
Q
Pearson r
A
- a widely used statistic for obtaining an index of the relationship between two variables
- when that relationship is linear and
- the two correlated variables are continuous (i.e., can theoretically take any value)
- also known as
- the Pearson coefficient of product-moment correlation and
- the Pearson correlation coefficient
41
Q
platykurtic
A
- a description of the kurtosis of a distribution that is relatively flat in its centre
p. 97
42
Q
positive skew
A
- when relatively few of the scores fall at the high end of the distribution
- positively skewed examination results may indicate the test was too difficult
- some easier questions would better discriminate at the lower end of the distribution
p.97
43
Q
quartile
A
- one of the three dividing points between the four quarters of a distribution
- each typically labelled
- Q1
- Q2
- Q3
- Q4
p.93
44
Q
range
A
- a descriptive statistic of variability
- derived by calculating the difference between the highest & lowest scores in a distribution
p. 93
45
Q
rank-order/rank-difference correlation coefficient
A
- an index of correlation
- statistic of choice when
- sample size is small, and
- both sets of measurement are ordinal
- also referred to as the Spearman’s rho
p. 110-111
46
Q
ratio scale
A
- a system of measurement where all things being measured can be rank-ordered
- the rank-ordering does imply something about exactly how much greater one ranking is than another
- equal intervals exist between each number on the scale
- all mathematical operations can be performed meaningfully
- because a true zero point exists
- few scales in psychology & education use ratio scales
p. 81-83
47
Q
raw score
A
- a straight forward, unmodified accounting of performance
- usually numerical
- typically used for evaluation or diagnosis
48
Q
scale
A
- 1) a system of ordered numerical or verbal descriptors
- usually occurring at fixed intervals
- used as a reference standard in measurement
- 2) a set of numbers or other symbols whose properties model empirical properties of the objects or traits to which numbers or other symbols are assigned
49
Q
scatter diagram
A
- a graphic description of correlation
- achieved by graphing the coordinate points for the two variables
- also referred to as a
- scatterplot
- scattergram, or
- bivariate distribution
p.111
50
Q
scattergram
A
- a graphic description of correlation
- achieved by graphing the coordinate points for the two variables
- also referred to as
- scatterplot
- scatter diagram or
- bivariate distribution
p.111
51
Q
scatterplot
A
- a graphic description of correlation
- achieved by graphing the coordinate points for the two variables
- also referred to as
- scatter diagram
- scattergram, or
- bivariate distribution
p.111
52
Q
semi-interquartile range
A
- a measure of variability
- equal to the
- interquartile range divided by two
p.94
53
Q
skewness
A
- an indication of the nature & extent to which symmetry is absent in a distribution
- a distribution is said to be
- skewed positively when relatively few scores fall at the positive end and
- skewed negatively when relatively few scores fall at the negative end
p.96-97
54
Q
Spearman’s rho
A
- an index of correlation
- statistic of choice when
- sample size is small, and
- both sets of measurement are ordinal
- also referred to as the
- rank-order correlation coefficient, and
- rank-difference correlation coefficient
p.110-111
55
Q
standard deviation
A
- a measure of variability
- equal to the square root of the averaged squared deviations about the mean
- also equal to the square root of the variance
p. 94-96
56
Q
standard score
A
- a raw score that has been converted from one scale into another
- the new scale has
- arbitrarily set M & SD
- is more widely used & readily interpretable
- examples of standard scores are
- z scores
- T scores
57
Q
stanine
A
- a standard score derived from a scale with
- a mean of 5 and
- a standard deviation of approx. 2
p.103-104
58
Q
T score
A
- a standard score
- calculated using a scale with
- a mean set at 50 and
- a standard deviation set at 10
- used by the developers of the MMPI
- named for Thorndike
p. 103, 429
59
Q
tail
A
- the area on the normal curve between
- 2 and 3 standard deviations above the mean, and
- -2 and -3 standard deviations below the mean
- a normal curve has two tails
p. 101
60
Q
variability
A
- an indication of how scores in a disrtibution are scattered or dispersed
p. 92-96
61
Q
variance
A
- a measure of variability
- equal to the
- arithmetic mean of the squares of the differences
- between the scores in a distribution
- and their mean
p.95, 146
62
Q
z score
A
- a **standard score **
- derived by calculating the difference between
- a particular raw score & the mean
- and then dividing by the standard deviation
- a z score expresses a score in terms of the number of standard deviation units the raw score is below or above the mean of the distribution
p. 102-103
