4 Flashcards
level of measurement
the relationship among the numbers we have assigned to the information
the relationship among the numbers we have assigned to the information
level of measurement
levels of measuremetn
four levels are nominal, ordinal, equal interval, and ratio
four levels are nominal, ordinal, equal interval, and ratio
levels of measurement
nominal
numbers are assigned to represent labels or categories of data only
frequency, mode, chi-square
numbers are assigned to represent labels or categories of data only
nominal
frequency, mode, chi-square
ordinal
numbers are assigned to rank-order data. However, the distances or values between numbers are not equal; they can vary
Frequency, mode, median, percentile, rank-order correlation
numbers are assigned to rank-order data. However, the distances or values between numbers are not equal; they can vary
ordinal
Frequency, mode, median, percentile, rank-order correlation
interval
numbers are also assigned to rank-order data, and the distance between numbers is judged to be equal. However, there is no absolute zero point (a number that indicates the complete absence of what is measured).
Frequency, mean, mode, median, standard deviation, Pearson product−moment correlation, t test, F test
numbers are also assigned to rank-order data, and the distance between numbers is judged to be equal. However, there is no absolute zero point (a number that indicates the complete absence of what is measured).
interval
Frequency, mean, mode, median, standard deviation, Pearson product−moment correlation, t test, F test
ratio
numbers are also assigned to rank-order data, and the distance between numbers is also equal, and there is an absolute zero point.
Frequency, mean, mode, median, standard deviation, Pearson product−moment correlation, proportion, t test, F test
numbers are also assigned to rank-order data, and the distance between numbers is also equal, and there is an absolute zero point.
ratio
Frequency, mean, mode, median, standard deviation, Pearson product−moment correlation, proportion, t test, F test
categorical data
data grouped according to a common property
data grouped according to a common property
categorical data
raw scores
the most basic scores calculated from a psychological test
the most basic scores calculated from a psychological test
raw scores
norm group
a previously tested group of individulas
a previously tested group of individulas
norm group
frequency distribution
an orderly arrangement of a group of numbers (or test scores)
Frequency distributions show the actual number (or percentage) of observations that fall into a range or category; they provide a summary and picture of group data
an orderly arrangement of a group of numbers (or test scores)
frequency distribution
Frequency distributions show the actual number (or percentage) of observations that fall into a range or category; they provide a summary and picture of group data
class intervals
a way to group raw scores so as to display them
a way to group raw scores so as to display them
class intervals
histogram
a bar graph used to represent frequency data in statistics
bar graph with spaces between them
a bar graph used to represent frequency data in statistics
histogram
normal curves
theoretical distributions that exist in our imagination as perfect and symmetrical, and actually consist of a family of distributions that have the same general bell shape—high in the middle and tapering to the ends
theoretical distributions that exist in our imagination as perfect and symmetrical, and actually consist of a family of distributions that have the same general bell shape—high in the middle and tapering to the ends
normal curves
what percentage of the population will score between the mean and 1 standard deviation?
34.1%
what percentage of the population will score between 1 and 2 standard deviation?
13.6%
What percentage of the population will score between 2 and 3 standard deviations?
2.1%
descriptive statistics
describe or summarize a distribution of test scores using numbers
describe or summarize a distribution of test scores using numbers
descriptive statistics
measure of central tendency
value that helps us understand the middle of a distribution or set of scores
mean
median
mode = which score occurs most often
value that helps us understand the middle of a distribution or set of scores
measure of central tendency
mean
median
mode
measures of variability
Numbers that represent the spread of the scores in the distribution, such as range, variance, and standard deviation.
Numbers that represent the spread of the scores in the distribution, such as range, variance, and standard deviation.
measures of variability
range
highest score minus the lowest score
variance
tells us whether individual scores tend to be similar to or substantially different from the mean
tells us whether individual scores tend to be similar to or substantially different from the mean
variance
standard deviation
square root of the variance
the most commonly used measure of variability in a distribution of test scores
A measure of variability that represents the degree to which scores vary from the mean.
A measure of variability that represents the degree to which scores vary from the mean.
standard deviation
correlation coefficient
a statistic that we typically use to describe the relationship between two or more distributions of scores
Using a correlation coefficient, we can relate one set of scores to another set to see whether the same individuals scored similarly on two different tests
a statistic that we typically use to describe the relationship between two or more distributions of scores
correlation coefficient
Normal distribution:
1 standard dviaion above and below =
2 standard deviation above and below =
3 standard deviations above and below =
1 = 68% 2 = 95% 3 = 99%
Pearson product−moment correlation coefficient
r
the coefficient measures the linear association between two variables, or sets of test scores, that have been measured on interval or ratio scales
used to calculate correlation coefficient
the coefficient measures the linear association between two variables, or sets of test scores, that have been measured on interval or ratio scales
Pearson product−moment correlation coefficient
Linear transformations
change the unit of measurement, but do not change the characteristics of the raw data in any way
percentages
z Scores
T Scores
change the unit of measurement, but do not change the characteristics of the raw data in any way
Linear transformations
Area transformations
change not only the unit of measurement, but also the unit of reference (for reading raw data)
percentiles: percentage of scores in a distribution that fall at or below a given raw score (1 of 2 definitions)
Stanines: a standard score scale with nine points that allows us to describe a distribution in words instead of numbers
change not only the unit of measurement, but also the unit of reference (for reading raw data)
Area transformations
norms
test scores achieved by some identified group of individuals
test scores achieved by some identified group of individuals
norms
norm-based interpretation
The process of comparing an individual’s test score to a norm group
The process of comparing an individual’s test score to a norm group
norm-based interpretation
types of norms
age norms and grade norms: allow us to determine at what age level or grade level an individual is performing
percentile ranks: it provides us with a way to rank individuals on a scale from 1% to 100%, making it relatively easy to interpret
Cautions with norms
although raw score on a test remains the same, our interpretation of their performance will differ depending on the norm group with which we compare his test score
look at size of the norm group
use up-to-date norms
careful wen using age and grade norms (smart 10 year old could be placed in grade 10)
