chapter 3 Flashcards
What are used to describe, make inferences from, and draw conclusions about numbers?
Statistical Tools
What is the act of assigning numbers or symbols to characteristics of things (people, events, etc.) according to rules?
Measurement
What are the guidelines for representing the magnitude (or some other characteristic) of the object being measured?
Rules Used to Assign Numbers
What is a set of numbers (or other symbols) whose properties model empirical properties of the objects to which the numbers are assigned?
Scale
What are the two ways to categorize scales?
Continuous Scale, Discrete Scale
What is a scale used to measure a continuous variable, where it is theoretically possible to divide any of the values of the scale?
Continuous Scale
What is a scale used to measure a discrete variable? Give an example.
Discrete Scale; Example: Male or Female
What does the division of a continuous scale depend on?
Factors such as the purpose of the measurement and practicality
What refers to the collective influence of all of the factors on a test score or measurement beyond those specifically measured by the test?
Error
What are some sources of error in measurement?
A distracting thunderstorm, Particular selection of test items the instructor chose to use for the test
What type of scale is continuous when used for psychological and educational assessment and is expected to contain some error?
Measuring Scale
What are the four levels or scales of measurement?
Nominal, Ordinal, Interval, and Ratio Scales
What determines whether statistical manipulation is appropriate?
The level or scale of measurement
What type of scales involve classification or categorization based on one or more distinguishing characteristics?
Nominal Scales
What arithmetic operations can be performed with nominal data?
Counting cases, determining proportions or percentages
What type of scales permit classification and rank ordering but have no absolute zero point?
Ordinal Scales
Who developed an intelligence test and believed intelligence data was ordinal in nature?
Alfred Binet
What survey uses the ordinal form of measurement?
Rokeach Value Survey
Why does zero have no meaning in an ordinal scale survey?
The number of units separating one score from another is unknown
What type of scale contains equal intervals between numbers but no absolute zero point?
Interval Scales
What type of scale has a true zero point, allowing all mathematical operations to be performed?
Ratio Scales
What is an example of ratio-level measurement used in neurological testing?
Hand grip test, timed perceptual-motor ability test
What level of measurement is used in psychology for intelligence, aptitude, and personality tests?
Ordinal level of measurement
A set of test scores arrayed for recording or study
Distribution
A straightforward, unmodified accounting of performance, usually numerical
Raw score
A list of all scores alongside the number of times each score occurred
Frequency Distribution
A frequency distribution where individual scores are used without grouping
Simple Frequency Distribution
A frequency distribution where test-score intervals replace individual scores
Grouped Frequency Distribution
What are test-score intervals called?
Class Intervals
A diagram or chart composed of lines, points, bars, or other symbols illustrating data
Graph
It allows easy understanding of a single score’s place in a distribution
Good graph
What are the types of graphs?
Histogram, Bar Graph, Frequency Polygon
A graph with vertical lines forming contiguous rectangles at the true limits of each test score
Histogram
What is the X-axis of a graph called, and what is placed on it?
Abcissa; Test Scores
What is the Y-axis of a graph called, and what is placed on it?
Ordinate; Frequency of occurrence
is a statistic that indicates the average or midmost score between
the extreme scores in a distribution.
Measure of central tendency
The sum of observations divided by the number of observations, denoted as “X bar”
Mean
The middle score in a distribution
Median
The most frequently occurring score in a distribution
Mode
An indication of how scores in a distribution are scattered or dispersed
Variability
The spread of data from the lowest to the highest value in the distribution
Range
The dividing points between the four quarters in a distribution
Quartiles
What is another tool that describes the amount of variability in a distribution?
Average distribution
The measure of variability equal to the square root of the average squared deviations about the mean/ a measure of how dispersed the data is in relation to the mean.
Standard deviation
The arithmetic mean of the squares of the differences between scores and their mean
Variance
The nature and extent to which symmetry is absent in a distribution
Skewness
When relatively few scores fall at the high end of a distribution
Positive Skew
When relatively few scores fall at the low end of a distribution
Negative skew
What does a negatively skewed test indicate?
The test was too easy
The steepness of a distribution at its center
kurtosis
A bell-shaped, smooth, mathematically defined curve that is highest at its center
A normal curve
A raw score converted to another scale with a set mean and standard deviation
Standard Score
A score indicating how many standard deviation units a raw score is above or below the mean
Z score
A score on a scale with a mean of 50 and a standard deviation of 10
T score
A contraction of “standard” and “nine” / a method of scaling test scores on a nine-point standard scale with a mean of five (5) and a standard deviation of two (2)
Stanine
A transformation that retains a direct numerical relationship to the original raw score
Linear formation of standard score
When the data are not normally distributed but need to be compared with normal distributions
Non-Linear formation
Stretching a skewed curve into the shape of a normal curve and creating a corresponding scale of standard scores
Normalizing a distribution
