Chapter 3 Flashcards
Are methods used to PROVIDE A CONCISE DESCRIPTION of a collection of quantitative information.
DESCRIPTIVE STATISTICS
Are 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.
INFERENTIAL STATISTICS
Act of assigning numbers or symbols to characteristics of things according to rules. The rules serves as a guideline for representing the magnitude. It always involves error.
MEASUREMENT
Set of numbers whose properties model empirical
properties of the objects to which the numbers are assigned.
SCALE
Interval/ratio. A scale used to measure
continuous variable. Always involves error.
CONTINUOUS SCALE
Nominal/ordinal used to measure a discrete
variable (ex. Female or male)
DISCRETE SCALE
Collective influence of all of the factors on a test error.
ERROR
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.
MAGNITUDE
A scale has the property of equal intervals if the 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.
EQUAL INTERVAL
Obtained when nothing of the property being measured exists.
This is extremely difficult/impossible for many
psychological qualities.
ABSOLUTE 0
Simplest form of measurement.
Used for naming or describing things. They
simply classify subjects into categories.
Arithmetic operations can be performed.
Ex.) Male or female
Ex.) yes/no responses
NOMINAL SCALE
Classifies in some kind of ranking order.
Individuals compared to others and assigned a rank.
Imply nothing about how much greater one ranking is than another.
Numbers/ranks do not indicate units of measure.
No absolute zero point.
ORDINAL SCALE
He believed that data derived from
intelligence test are ordinal in nature.
Alfred Binet
Assign numbers to indicate whether individuals are less than, greater than, or equal to each other.
Can take average.
Shows difference between scores.
INTERVAL SCALE
Have “true” value of zero.
Ex.) measuring amount of pressure hand can
exert
RATIO SCALE
Set of scores arrayed for recording or study.
DISTRIBUTION
Straightforward, unmodified accounting of performance, usually numerical.
RAW SCORE
All scores listed alongside the
number of times each score occurred.
FREQUENCY DISTRIBUTION
Test-score intervals (class intervals), replace the actual test scores
Ex.) Highest and lowest class intervals= upper and lower limits distribution.
GROUPED FREQUENCY DISTRIBUTION
Graph with vertical lines drawn at the true limits of each test score (or class interval) forming TOUCHING rectangles- midpoint in center of bar.
HISTOGRAM
Rectangles DON’T touch.
BAR GRAPH
Data illustrated with continuous line connecting the points where test scores or class intervals meet frequencies.
FREQUENCY POLYGON
Statistic that indicates the average or midmost score between the extreme scores in a distribution.
MEASURE OF CENTRAL TENDENCY
“X bar”
Sum of observations divided by number of
observations.
Sigma (X/n)
Used for interval or ratio data when distributions are relatively normal.
ARITHMETIC MEAN
The Middle Score.
Used for ordinal, interval, and ratio data.
Especially useful when few scores fall at
extremes.
MEDIAN
Most frequently-occurring score.
Bimodal distribution- 2 scores both have highest frequency.
MODE
2 scores both have highest frequency.
BIMODAL DISTRIBUTION
Indication of how scores in a distribution are scattered or dispersed.
VARIABILITY
Any statistics that describe the amount of variation in a distribution.
MEASURE OF VARIABILITY
Difference between the highest and lowest
scores.
Quick but gross description of the spread of
scores.
RANGE
Distribution is split up by 3 quartiles, thus making 4 quarters each representing 25% of the scores.
INTERQUARTILE AND SEMI-INTERQUARTILE RANGE
Measure of variability equal to the difference between Q3 and Q1.
INTERQUARTILE RANGE
Interquartile range divided by 2.
SEMI-INTERQUARTILE
Is the 25th percentile.
FIRST QUARTILE
The median or the 50th percentile.
SECOND QUARTILE
Is the 75th percentile.
THIRD QUARTILE
