Ch2: Measurement, Central Tendency, and Variability Flashcards
Nominal Scale
categorical scale, qualitative measurement, categorical measurement: different entities receive different values
Ordinal Scale
numbers to covey less than and more than information
Summative Scale
require respondents to assign numbers to represent attitudes or judgments
Interval Scale
Fixed distances between the number represent equal intervals
Ratio Scale
Has an absolute zero point, where zero means the absence of the property
Qualitative measurement
obtained from using a nominal scale of measurement
Categorical variables
Nonmetric Variables
Dichotomous variables (where there are only two values or categories)
Grouped variables
Classfication variables
Quatitative measurement
Continous variables
Metric variables
Ungrouped variables
Central tendency
Measures of central tendency provide and index (or single-value summary) of the most typical score in a set of distribution of scores
Variability
how scores within a group or treatment condition vary or deviate from one another
Y
scores on the dependent variable
Yi
represent any scroe and thus is applicable to every score
n
the number of scores within a group or treatment condition
N
the entire sample size
Y bar
the mean of the scores
Variance
how dispersed the scores are with respect to the mean
Sum of squares
SS, which becomes the numerator of the variance formula
degrees of freedom
a denominator that adjust the sum of squares
S2 =
SS/df
ANOVA
allows us to partition (divide) the total variance measured in the study into its sources or component parts
ANOVA
a general statitistical technique that we use to compare the scores in one condition to those of one or more other conditions
Three classes of ANOVA designs
between-subjects design, within-subjects or repeated-measures designs, and mixed-designs
one-way between subject design
only one independent variable
MS
mean square: the variance of each respective source of variance
Sources of variance
represents a portion or partition of the total variance
Factor, factors, or treatments
independent variables
S/A
subjects within the level of Factor A
Total sum of squares
ignore the fact that there are multiple groups involved in the study and simply pool all of the data together
grand mean YT bar
mean based on all of the individual scores
SSA
between-groups sum of squares
Yj bar
the mean for a given group
error variance
these other variables contribute measurement variability to the study, and that unaccounted for variability within each group
SS S/A
the within-group sum of squares
degree of freedom for the total variance
equal to the total number of observations minus 1
degree of freedom for the between-groups effect
equal to the number of levels of independent variable minus one
degree of freedom for the error variance
equal to the sum of the degrees of freedom for each of the groups
