Appraisal - Chapter 3 notes - Drummond Flashcards
statistic
numerical representation of information
descriptive statistics
type of statistics that play a role in interpreting instrument scores; used to describe and summarize large amounts of data
frequency
simplest descriptive statistic used in assessment; the count of occurrences of a particular test score
mean, median, frequency and mode
3 types of frequencies in assessment
inferential statistics
used when we want to make inferences about a large group of people by examining characteristics about randomly selected subgroups from populations
populations
large groups of people
variable
anything can take on more than one value; can be visible (gender, eye color) or invisible (personality, intelligence or aptitude)
measurement
process of assigning numbers or symbols to represent objects, traits or behaviors (variables) according to a set of logical rules
scales of measurement
ways in which variables are defined and characterized
nominal, ordinal, interval and ratio
4 scales of measurement
magnitute
inherent order of numbers form smaller to larger
equal intervals
equal distance between adjacent points on the scale
absolute/true zero
point representing the absence of the property being measured
nominal scale
used to describe qualitative variables that can be categorized based on one or more distinguishing characteristics; only represents names and has non of the 3 qualities of scales of measurement
no absolute zero point
no absence of the variable being measured
internal locus of control
individuals with this tend to attribute outcomes of events to their own control
external locus of control
individuals with this tend to attribute outcomes of events to external circumstances
Nowicki-Strickland scale
measures locus of control; low scores indicate internality; high scores indicate externality
distribution
a set of scores
frequency of distribution
takes a disorganized set of scores and places them in order, usually on a table or graph
group
series of scores vs. individual ones; class interval
graph
diagram or chart made up of lines, points, bars or other symbols that give a pictorial representation of the distribution of test scores
histogram
graph that uses vertical lines and bars to portray distribution of test scores
x axis
abscissa; horizontal axis representing class intervals
y axis
ordinate axis; represents frequencies of scores appearing at each class interval
frequency polygon
variation of the hisotgram; bars are replaced by lines connecting the midpoint of each class interval
symmetrical distribution
each side of the curve is a mirror image of the other
skewed
frequency curve that’s not symmetrical; something out of proportion
positively skewed
majority of scores fell near the lower end of scale
negatively skewed
majority of students scoring poorly on a test
kurtosis
statistic that reflects the peakedness or flatness of a distribution relative to a normal distribution
meskurtic, leptokurtic or platykurtic
3 types of distributions
measures of central tendency
ways to describe a distribution based on the typical or average performance of test scores
mean, median and mode
3 common measures of central tendency
mean
the most frequently used measure of central tendency; the arithmetic average score in a distribution; used with interval or ratio scales and whenever additional statistical analysis is needed
total the test scores and divide the sum by the number of individuals who took the test
how mean is calculated
median
the middle score or the score that divides the distribution in half
mode
score of numerical value that appears most frequently in a set of scores
outliers
extreme scores
variability
degree that scores are spread out and differ from one another
measures of variability
statistics that describe the dispersion of scores
range, variance and standard deviation
3 commonly used measures of variability
range
quick measure of the spread of scores
subtracting the lowest score from the highest score
how the range is computed
variance
the average amount of variability in the group of scores
standard deviation
most frequently used measure of variability; the avg. distance of test scores from the mean
normal curve/distribution or bell curve
visual representation of an ideal or theoretical distribution consisting of an infinite number of scores; based on probability theory
measure of relationship
shows the degree of relationship or correlation between 2 variables or scors
correlation coefficient
statistic used to measure correlation
positive correlation
2 variables move in the same direction
negative correlation
2 variables move in opposite or inverse directions
strength
magnitude of the relationship between 2 variables
perfect positive correlation
higher values on one variable directly relate to higher values on the second variable
regression
statistical method related to correlation; primarily used for prediction; an analysis of relationships among variables for understanding how 1 variable might predict another
simple linear regression
regression analysis used to predict the value of one variable
regression line or line of best fit
represents the association between the 2 variables that illustrates the linear relationship between them
error
deviation of the points from the line
multiple regression
same as a simple linear regression except that it attempts to predict the dependent variable by a set of independent variables
factor analysis
analyzes the relationship between variables but not for purposes of predicting a dependent variable; objective it so simplify the description data by reducing the # of necessary variables
data-reduction technique
used to analyze relationships between large #’s of variables
