Non-parametric Analysis User Guide
Transcript of Non-parametric Analysis User Guide
InVivoStat User Guides – Non-parametric Analysis Version 4.3 November 2021
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Non-parametric
Analysis
User Guide
InVivoStat User Guides – Non-parametric Analysis Version 4.3 November 2021
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Contents
1 Introduction ......................................................................................... 3
2 Dataset format ..................................................................................... 3
3 Analysis procedure .............................................................................. 4 3.1 Select the analysis module ........................................................................................................ 4 3.2 Select the dataset to be analysed ............................................................................................... 4 3.3 Select the response to analyse and terms to include in the statistical model ............................ 4 3.4 Select the analysis results ......................................................................................................... 5 3.5 Define the control group ........................................................................................................... 5 3.6 Run the analysis ........................................................................................................................ 6
4 Output results ...................................................................................... 6
5 Controlling the output ........................................................................ 7
6 Test dataset example output .............................................................. 9 6.1 InVivoStat options .................................................................................................................... 9 6.2 Sample output ........................................................................................................................... 9
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1 Introduction
The Non-parametric Analysis module in InVivoStat is available from the Statistics
drop-down menu entitled ‘Non-parametric Analysis’. The user interface is:
The Non-parametric Analysis module performs the Kruskal–Wallis test, the
Mann-Whitney test (also known as Wilcoxon Rank Sum Test), Steel’s all
comparisons back to control test and the Behrens-Fisher all pairwise tests. The
module also performs Friedman’s test and the Wilcoxon Signed Rank test if a
blocking factor is selected.
2 Dataset format
The Non-parametric Analysis module accepts data in the single measures format, for
example:
Response Treatment Block
0.998758912 x 1
0.911332819 x 2
0.410939792 x 3
0.051020205 x 4
0.280761538 x 5
0.877216432 y 1
0.353903886 y 2
0.901387615 y 3
0.739097386 y 4
0.886753925 y 5
0.021624508 y 6
0.585623196 y 7
0.616738341 y 8
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3 Analysis procedure
The steps required to perform an analysis are described in this section.
3.1 Select the analysis module
The analysis begins by selecting the
Non-parametric Analysis module from
the drop-down list of available modules
Additional Analysis →
Non-parametric Analysis
3.2 Select the dataset to be
analysed
Once the module is selected, the dataset
is chosen from the drop-down list of
available datasets.
Click ‘Submit’.
3.3 Select the response to
analyse and terms to
include in the statistical
model
Once the dataset has been selected, the
user selects the response variable to
analyse by clicking on the Response
box and selecting the response variable
to analyse.
Similarly, the user can select the
(categorical) treatment factor and, when
required, a blocking factor.
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3.4 Select the analysis results
There are several results that are
available. These are selected before
running the analysis and include:
1) Overall test
The overall test between the treatment
levels (either the Mann-Whitney test, if
there are only two levels of the
treatment factor, or the Kruskal-Wallis
test if there are more than two levels of
the treatment factor).
2) All treatment comparisons
InVivoStat calculates the Behrens-
Fisher all pairwise tests and also all
pairwise Mann-Whitney tests. Behrens-
Fisher tests are recommended in many
texts, although the results generated
within InVivoStat have not been
independently verified.
3) Comparisons back to control
InVivoStat performs the Steel’s all
comparison back to one test. The user is
also required to select the control group
from a drop-down menu.
4) Significance level
The significance level default is 0.05, or
5%, although this can be changed.
3.5 Define the control group
If the ‘Comparisons back to control’
analysis is selected, the user should
define the control group to compare
back to.
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3.6 Run the analysis
Click ‘Submit’ to run the analysis.
4 Output results
Response
InVivoStat identifies the response being analysed.
Summary data
A table of summary statistics including the median, the interquartile range (Q1 and
Q3, the minimum and maximum observation. Each row of the table corresponds to a
treatment group.
Boxplot
A boxplot of the data, categorised by the treatment factor.
Overall test results
A table of test results, depending on the option selected by the user. This can be either
Kruskal-Wallis or Mann-Whitney test, depending on the number of treatments,
Behrens-Fisher and all pairwise Mann-Whitney tests or Steel’s all comparisons back
to one. If a blocking factor is selected InVivoStat performs Friedman’s test or the
Wilcoxon Signed Rank test.
Analysis conclusions
A summary of the analysis conclusions, at the selected level of significance.
References
A list of references for the methods applied in the analysis.
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5 Controlling the output
The user has the ability to control various aspects of the output. These are available in
the ‘Output Options’ dialogue:
Users can manipulate various plot
characteristics including line size, fonts
and marker size/type.
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The user has control over all text
included on the plots, for example text
position, size and font.
The user has control over the colour
scheme employed by InVivoStat,
including an option to produce all plots
in black & white.
Further information on these options can be found in the Getting Started User Guide.
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6 Test dataset example output
6.1 InVivoStat options
6.2 Sample output
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