to select a d escriptive statistic
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To Select a D escriptive Statistic. Table. Nominal or Ordinal. Graph. Interval or Ratio. No. Interval o r Ratio. Yes. Ordinal. Nominal. Mean. Median. No. Mode. Yes. Location relative to the mean. Standing relative to other scores. - PowerPoint PPT PresentationTRANSCRIPT
To Select a Descriptive Statistic
Present entire distribution Table or graph?
Frequency Distribution Table
Scale of measurement?
Bar Graph
Histogram or Polygon
Summarize entire distribution
Central tendency Scale of measurement?
Skewed, open-ended, or
undetermined scores?
Mean
MedianMedian
Mode
Variability What measure of central tendency?
Standard Deviation
Semi-interquartile range or Range
Nominal scale?
Range or Semi-Interquartile Range
None
Describe individual score
z-Score
Percentile Ranks
Table
Graph
Nominal or Ordinal
Interval or Ratio
Location relative to the mean
Standing relative to other scores
No
YesInterval
or Ratio
Nominal
Ordinal
No
Yes
MedianMean
Mode
To Select a Statistic to Measure theRelationship Between Two Variables
Data consist of 2 scores for each
individual
How many dichotomous
variables?
Both variables measured on
interval or ratio scale?
Measure linear or monotonic
relationship?
Pearson Correlation
Spearman Correlation
Both variables measured on
ordinal scales? If possible, rank order both variables and use Spearman. Otherwise, convert to frequency
data and use chi-square test for independence.
Point-Biserial Correlation
Phi-Coefficient
Data consist of frequency values for each category
Chi-Square Test for Independence
None
Two
Only oneNo
NoYes
YesMonotonic
Linear
To Select a Parametric Statisticto Evaluate Group Differences
How many separate samples?
How many scores for each subject?
Is σ known?
z-score Test
Single-Sample t-Test
Related-Samples t-Test
Repeated-Measures ANOVA
Matched or independent samples?
Related-Samples t-Test
Independent-Measures t-Test
Matched or independent samples?
Repeated-Measures ANOVA
How many independent variables?
Single-Factor ANOVA
Two-Factor ANOVA
One
Two
More than two
No
Yes
One
Two
More than two
Independent
Matched
Independent
Matched
One
Two
To Select a Nonparametric Statisticto Evaluate Group Differences
How many separate samples?
How many scores for each subject?
How many categories of measurement?
Chi-SquareGoodness of Fit
Binomial Test
Can difference scores be ranked?
Sign Test
Wilcoxon Test
Matched or independent samples?
Can difference scores be ranked?
Can scores be ranked with few tied values?
Mann-Whitney
Chi-Square Test for Independence
Median Test
Independent samples only
Are scores discrete or continuous?
Median Test
Chi-Square Test for Independence
More than two
One
Two
Independent
Matched
Two
OneOnly two
Two or more
Yes
No
Yes
No
No
Discrete
Continuous