Upload
alijah-durnell
View
266
Download
1
Tags:
Embed Size (px)
Citation preview
David Normando
A PowerPoint®-based guide to assist in choosing the suitable statistical test.
NOTE: This presentation has the main purpose to assist researchers and students in choosing the
appropriate statistical test for studies that examine one variable (Univariate). Some multivariates analyses are also included.
Please proceed to the next page ...
If you have any suggestion, criticism, please contact the author by e-mail: [email protected]
David Normando
What do you want to do? For an answer, click on the button
1) I want to assess whether my data have a Normal distribution
2) I want to compare groups (Looking for differences between samples)
3) I want to make correlation or regression analysis between variables.
4) I want to check the replicability of data (analysis of random and systematic error)
5) I would choose the appropriate graph to my data.
David Normando
Tests for Data Analysis Distribution- NormalityNormal distribution is requested when using continuos data and n<30Normal distribution is requested when using continuos data and n<30
You may choose the test according to sample size.
Use D’Agostino, Use D’Agostino, ifif n n≥≥1010
Use D’Agostino-Pearson, Use D’Agostino-Pearson, ifif nn≥≥2020
Use Lilliefors or Shapiro-Wilk, Use Lilliefors or Shapiro-Wilk, for anyfor any n value n value
Back to beginningBack to beginning
David Normando
What kind of data you have? (Click on the button).
Nominal
Ordinal
NUMERICALNUMERICALContinuousContinuous
NonparametricCategorical data
Parametric(mean)
Ex: height / length / weight (Assuming a normal distribution on n>30)
Ex: Frequency: Yes / No Race Gender
Ex: Middle (1) / Moderate(2) Severe (3)
Comparing groups (samples)
Back to beginningBack to beginning
How to check Normality ?How to check Normality ?
David Normando
Numerical Data (parametric) If the distribution is not Normal,
skip to "Abnormal" ABNORMAL
How many groups (samples) do you have?
1
2
>2
David Normando
Are your samples paired or dependent?
No
Yes
Not sure? Not sure? Dependent Samples mean: Dependent Samples mean:
Before X After Before X After Left Side X Right Side Left Side X Right Side
T1 x T 2 x T3T1 x T 2 x T3
Numerical Data (parametric) If the distribution is not Normal, skip to "Abnormal"
ABNORMAL
David Normando
Answer: one sample t test
Back to beginningBack to beginning
Numerical Data (parametric) If the distribution is not Normal,
skip to "Abnormal" ABNORMAL
David Normando
Answer: Independent t testor ANOVA.
Back to beginningBack to beginning
Numerical Data (parametric) If the distribution is not Normal,
skip to "Abnormal" ABNORMAL
David Normando
Answer: Paired t test or ANOVA for repeated measurements..
Back to beginningBack to beginning
Numerical Data (parametric) If the distribution is not Normal,
skip to "Abnormal" ABNORMAL
David Normando
Answer: Analysis of Variance (ANOVA)or MANOVA (Multiple Analysis of Variance), if you have >1 variable.
Numerical Data (parametric) If the distribution is not Normal,
skip to "Abnormal" ABNORMAL
Back to beginningBack to beginning
David Normando
Ordinal Categorical Data (Nonparametric)
2
>2
How many groups (samples) do you have ?
David Normando
No
Yes
Ordinal Categorical Data (Nonparametric)
Not sure? Not sure? Dependent Samples mean: Dependent Samples mean:
Before X After Before X After Left Side X Right Side Left Side X Right Side
T1 x T 2 x T3T1 x T 2 x T3
Are your samples paired or dependent?
David Normando
No
Yes
Ordinal Categorical Data (Nonparametric)
Not sure? Not sure? Dependent Samples mean: Dependent Samples mean:
Before X After Before X After Left Side X Right Side Left Side X Right Side
T1 x T 2 x T3T1 x T 2 x T3
Are your samples paired or dependent?
David Normando
Answer: Mann-Whitney test
Back to beginningBack to beginning
Ordinal Categorical Data (Nonparametric)
David Normando
Answer: Wilcoxon (signed rank test) or Signal test.
Back to beginningBack to beginning
Ordinal Categorical Data (Nonparametric)
David Normando
Answer: Kruskal-Wallis’ Test
Back to beginningBack to beginning
Ordinal Categorical Data (Nonparametric)
David Normando
Answer: Friedman’s Test
Back to beginningBack to beginning
Ordinal Categorical Data (Nonparametric)
David Normando
Nominal Categorical Data (Nonparametric)
2
>2
How many groups (samples) do you have ?
David Normando
No
Yes
Nominal Categorical Data (Nonparametric)
Not sure? Not sure? Dependent Samples mean: Dependent Samples mean:
Before X After Before X After Left Side X Right Side Left Side X Right Side
T1 x T 2 x T3T1 x T 2 x T3
Are your samples paired or dependent?
David Normando
No
Yes
Nominal Categorical Data (Nonparametric)
Not sure? If some of the cells in the contingency table give
values (expected) lower than 5.
Is there any expected value <5 ?
David Normando
No
Yes
Nominal Categorical Data (Nonparametric)
Not sure? Not sure? Dependent Samples mean: Dependent Samples mean:
Before X After Before X After Left Side X Right Side Left Side X Right Side
T1 x T 2 x T3T1 x T 2 x T3
Are your samples paired or dependent?
David Normando
Answer: Chi-square (x²) test or Binomial Test, if using 2 samples and proportion (%)
Back to beginningBack to beginning
Nominal Categorical Data (Nonparametric)
David Normando
Answer: Cochran’s test (absolute or relative frequence: %)
Nominal Categorical Data (Nonparametric)
Back to beginningBack to beginning
David Normando
Answer: McNemar’s test
Back to beginningBack to beginning
Nominal Categorical Data (Nonparametric)
David Normando
Answer: Exact Fisher’s test
Nominal Categorical Data (Nonparametric)
Back to beginningBack to beginning
David Normando
Correlation or Regression Analysis
Ordinals
Numerical
Nominal
What kind of data you have? (Click on the button).
Ex: height / length / weight (Assuming a normal distribution)
Ex: Frequency: Yes / No Race Gender
Ex: Middle (1) / Moderate(2) Severe (3)
How to check Normality ?How to check Normality ?
NonparametricCategorical data
Parametric(mean)
David Normando
Numerical Data (parametric) If the distribution is not Normal,
skip to "Abnormal" ABNORMAL
How many variables do you have?
2
>2
David Normando
Answer: Pearson’s Correlation
Simple Linear Regression
Back to beginningBack to beginning
ABNORMAL
Correlation tests or regression analysis to Continuos data
If the distribution is not Normal, skip to "Abnormal"
David Normando
Answer: Pearson’s Correlation (parcial) or Canonical Correlation
Multiple Linear Regression
Back to beginningBack to beginning
ABNORMAL
NOTE: For Correlation all variables examined must have a Normal Distribution.For Linear Regression dependent variable must have a Normal Distribution
How to check Normality ?How to check Normality ?
Correlation tests or regression analysis to Continuos data
If the distribution is not Normal, skip to "Abnormal"
David Normando
Answer : Spearman or Kendal Correlation
Back to beginningBack to beginning
Correlation test to Ordinal data
(nonparametric)
David Normando
How many variables do you have?
2
>2
Correlation and Regression Analysisto Nominal data (nonparametric)
David Normando
Answer: Contingency coefficient C
Simple Logistic Regression
Correlation test to Nominal data
(nonparametric)
Back to beginningBack to beginning
David Normando
Answer: Contingency coefficient C
Multiple Logistic Regression
Correlation test to Nominal data
(nonparametric)
Back to beginningBack to beginning
David Normando
Replicability or Reproducibility (Systematic error)
OrdinalOrdinal
NumericalNumerical
NominalNominal
What kind of data you have? (Click on the button).
Ex: height / length / weight (Assuming a normal distribution)
Ex: Frequency: Yes / No Race Gender
Ex: Middle (1) / Moderate(2) Severe (3)
NonparametricCategorical data
Parametric(mean)
How to check Normality ?How to check Normality ?
David Normando
Answer: Parametric test for dependent data
Note: Intraclass correlation can be used, if you would like to check the association between 2 or more measurements.
Replicability or Reproducibility (Systematic error for numerical data)
2 samples2 samples >2 samples>2 samples
ABNORMAL
Back to beginningBack to beginning
For random or casual error , you may use TEM (technical error measurement):
D= difference between repeated measures n=number of individuals
David Normando
Answer: Weighted Kappa
Replicability or Reproducibility (Systematic error for ordinal data)
2 sample > 2 samples
NOTE: in case of an ordinal variable, nonparametric tests for paired or dependent data can also be used
Back to beginningBack to beginning
David Normando
Answer: Kappa
Back to beginningBack to beginning
Replicability or Reproducibility (Systematic error for Nominal data)
David Normando
Nominal
Ordinal
NumericalParametric(mean)
Graph Selection
What kind of data you have? (Click on the button).
Ex: height / length / weight (Assuming a normal distribution)
Ex: Frequency: Yes / No Race Gender
Ex: Middle (1) / Moderate(2) Severe (3)
Back to beginningBack to beginning
NonparametricCategorical data
David Normando
Comparing Independent Samples
Making Data Correlation or regression
Comparing Dependent Samples (paired)
Graph Selection
Not sure? Not sure? Dependent Samples mean: Dependent Samples mean:
Before X After Before X After Left Side X Right Side Left Side X Right Side
T1 x T 2 x T3T1 x T 2 x T3
David Normando
BOX-PLOT - Comparing Groups.Continuous or Ordinal Data (Score)
This chart describes the measure of central tendency (MEAN for continuos data or MEDIAN for Ordinal This chart describes the measure of central tendency (MEAN for continuos data or MEDIAN for Ordinal data), measures of dispersion (Standard deviation for parametric data or interquartiles deviation for data), measures of dispersion (Standard deviation for parametric data or interquartiles deviation for
Ordinal data) and the whiskers (maximum and minimum values )Ordinal data) and the whiskers (maximum and minimum values )
BackBack
Outlier: an observation that Outlier: an observation that is numerically distantis numerically distantfrom the rest of the data. from the rest of the data.
David Normando
Line graph for longitudinal data
This chart describes the measure of central tendency (mean for Continuos data or median This chart describes the measure of central tendency (mean for Continuos data or median for Ordinal data) longitudinallyfor Ordinal data) longitudinally
BackBack
David Normando
Graphic for Correlation Tests or Regression Analysis
BackBack
David Normando
Bar/Column GraphicNominal data (frequency)
BackBack