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
measurement
* **assigning** numbers or symbols to characteristics of people or objects
* according to **rules**
p.78-79
26
measure of central tendency
* one of three statistics indicating the **average** or **middlemost score** between the extreme scores in a distribution
1. **mean** - ratio level
2. **median** - ordinal (takes the order of scores into account)
3. **mode** - nominal
p.89
27
measure of variability
* a statistic indicating **how scores** in a distribution are **scattered** or **dispersed**
* common measures of variability are
* **range**
* **standard deviation**
* **variance**
p.92
28
median
* a measure of **central tendency**
* derived by identifying the **middlemost score** in a distribution
p. 89-91
29
mesokurtic
* a description of the **kurtosis** of a distribution
* that is **neither** extremely **peaked nor flat** in its centre
p.97
30
meta-analysis
* a family of techniques
* used to statistically **combine** information **across studies**
* to produce **single estimates** of the statistics being studied
p. 115
31
mode
* a measureof **central tendency**
* derived by identifying the **most frequently occurring** score in a distribution
p. 89, 91-92
32
negative skew
* 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
nominal scale
* 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
nonlinear transformation
* 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
normal curve
* **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
normalized standard score scale
* 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
normalizing a distribution
* 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
ordinal scale
* 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
outlier
1. an extremely **atypical plot** point in a scatterplot
2. any extremely **atypical finding** in research
p.111
40
Pearson *r*
* 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
platykurtic
* a description of the **kurtosis** of a distribution that is relatively **flat in its centre**
p. 97
42
positive skew
* 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
quartile
* one of the three **dividing points** between the four quarters of a distribution
* each typically labelled
* Q1
* Q2
* Q3
* Q4
p.93
44
range
* a descriptive statistic of **variability**
* derived by calculating the **difference** between the **highest & lowest scores** in a distribution
p. 93
45
rank-order/rank-difference correlation coefficient
* 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
ratio scale
* 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
raw score
* a straight forward, **unmodified** accounting of performance
* usually **numerical**
* typically used for **evaluation or diagnosis**
48
scale
* 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
scatter diagram
* 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
scattergram
* 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
scatterplot
* 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
semi-interquartile range
* a measure of **variability**
* equal to the
* **interquartile range** **divided by two**
p.94
53
skewness
* 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
Spearman's rho
* 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
standard deviation
* 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
standard score
* 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
stanine
* a standard score derived from a scale with
* a mean of 5 and
* a standard deviation of approx. 2
p.103-104
58
*T s*core
* 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
tail
* 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
variability
* an indication of how scores in a disrtibution are scattered or **dispersed**
p. 92-96
61
variance
* 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
z score
* 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
