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


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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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Non-parametric Analysis User Guide

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