CH3 Flashcards
this term refers to the act of assigning numbers or symbols to characteristics of things (people, events, whatever) according to rules
measurement
what does noir mean?
noir means or is a useful acronym for the levels of measurement
nominal
ordinal
interval
ratio
what is the difference between discrete and continuous variables
discrete variables have a sample space that can be counted but a continuous variable has fractions or numbers with as many decimals as needed
example:
discrete = 1, 2, 3, 4, 5
continuous = 1, 1.1, 1.2, 1.3, 1.4
this term refers to the collective influence of all of the factors on a test
score or measurement beyond those specifically measured by the test or measurement
error
JUST THINK:
The scale with which we are all perhaps most familiar is the common bathroom scale. How are a psychological test and a bathroom scale alike?
How are they different? Your answer
may change as you read on.
open-ended but a psychological test can measure the intelligence of a person or rather something intangible
these scales have meaningful distances between numbers
interval scale
JUST THINK:
What are some other examples of interval scales?
grade because you can never get a 0.00
shoe size
do interval scales have an absolute zero point?
no
this term refers to a set of test scores arrayed for recording or study
distribution
JUST THINK:
What are some other examples of ratio scales?
test scores = if 0, no correct answers
battery power = if 0, no more power left
this term refers to a straightforward, unmodified accounting of performance that is usually numerical
raw score
with this, all scores are listed alongside the number of times each score occurred
frequency distribution
in this kind of frequency distribution, test-score intervals replace the actual test scores
grouped frequency distribution
this refers to a diagram or chart composed of lines, points, bars, or other symbols that describe and illustrate data
graph
this is a graph with vertical lines drawn at the true limits of each test score (or class interval), forming a series of contiguous rectangles
histogram
in this type of graph, numbers indicative of frequency also appear on the Y-axis, and reference to some categorization (e.g., yes/no/maybe, male/female) appears on the X-axis
bar graph
this term refers to a statistic that indicates the average or midmost score
between the extreme scores in a distribution
measure of central tendency
in this graph, data is illustrated by a
continuous line connecting the points where test scores or class intervals (as indicated on the X-axis) meet frequencies (as indicated on the Y-axis)
frequency polygon
what is the most commonly used measure of central tendency
the mean or the average
what is the arithmetic mean equal to?
the arithmetic mean is equal to the sum of the observations divided by the number of observations
how do you know the median if the number of scores is an odd number?
the median will be the score that is exactly in the middle, with one-half of the remaining scores lying above it and the other half of the remaining scores lying below it
what is the median?
the median is the middle score in a distribution
how do you know the median if the number of scores is an even number?
the median can be calculated by determining the arithmetic mean of the two middle scores
what is the mode?
the most frequently occurring score in a distribution of scores
what is a bimodal distribution?
a distribution that has two scores that occur with the highest frequency
how can the mode be useful in an analysis?
when assessing consumers’ recall of a commercial by means of interviews, a researcher might be interested in which word or words were mentioned most by interviewees
this term refers to an indication of how scores in a distribution are scattered or dispersed.
variability
JUST THINK:
Devise your own example to illustrate how the mode, and not the mean, can be the most useful measure of central tendency
open-ended
what are some measures of variablity?
the range, the interquartile range, the semi-interquartile range, the average deviation, the standard deviation, and the variance
what is the range of a distribution?
the range of a distribution is equal to the difference between the highest and the lowest scores
this term refers to a measure of variability equal to the difference between Q3 and Q1
Like the median, it is an ordinal statistic
interquartile range
what are the four quarters in a distribution called?
quartiles
what is a standard score?
a standard score is a raw score that has been converted from one scale to
another scale, where the latter scale has some arbitrarily set mean and standard deviation
this measure of variability is equal to the interquartile range divided by 2
semi-interquartile range
what does it mean when a distribution has a negative skew?
A distribution has a negative skew when relatively few of the scores fall at the low end of the distribution
what does it mean when a distribution has a positive skew?
A distribution has a positive skew when relatively few of the scores fall at the
high end of the distribution
what is kurtosis?
the term used to refer to the steepness of a distribution in its center
what are the three descriptions of kurtosis?
platykurtic - relatively flat
leptokurtic - relatively peaked
mesokurtic - somewhere in the middle
what does a tail mean?
The area on the normal curve between 2 and 3 standard deviations above the mean is referred to as a tail
this indicates how many standard deviation units the raw score is below or above the mean of the distribution
z score
in this transformation, a standard score is one that retains a direct numerical relationship to the original raw score
linear transformation
this is a number that provides us with an index of the strength of the relationship between two things
coefficient of correlation
when is a nonlinear transformation required?
A nonlinear transformation may be required when the data under consideration are not normally distributed yet comparisons with normal distributions need to be made.
this term refers to an expression of the degree and direction of correspondence between two things
correlation
what is pearson r?
Pearson r is the Pearson correlation coefficient and the statistical tool of choice when the relationship between the variables is linear and when the two variables being correlated are continuous
this refers to the indication of how much variance is shared by the x and the y variables
coefficient of determination
how are scatterplots useful?
Scatterplots are useful because they provide a quick indication of the direction and magnitude of the relationship, if any, between the two variables
what is a scatterplot?
a scatterplot is a simple graphing of the coordinate points for values of the X-variable (placed along the graph’s horizontal axis) and the Y-variable (placed along the graph’s
vertical axis)
what is a meta-analysis?
Meta-analysis may be defined as a family of techniques used to statistically combine information across studies to produce single estimates of the data under study
what is an outlier?
an outlier is an extremely atypical point located at a relatively long distance—an outlying distance—from the rest of the coordinate points in a scatterplot
what is effect size?
the estimates derived from a meta-analysis
this term refers to professional practice that is based on clinical and research findings
evidence-based practice
