Difference between revisions of "2.1.8 Randomisation"

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(C. Resources)
(C. Resources)
 
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Randomisation is a process of random assignment of experimental units to treatment conditions:
 
Randomisation is a process of random assignment of experimental units to treatment conditions:
  
occurrence of one event should have no influence on the next event (independence principle)
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* occurrence of one event should have no influence on the next event (independence principle);
randomisation sequence cannot be based on an easily memorizable and reproducible sequence (randomness principle)
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* randomisation sequence cannot be based on an easily memorizable and reproducible sequence (randomness principle).
 +
 
 
Randomization serves three main purposes:
 
Randomization serves three main purposes:
  
enables the application of statistical tests based on the central limit theorem
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* enables the application of statistical tests based on the central limit theorem;
prevents a potential impact of the selection bias due to differing baseline or confounding characteristics of the subjects
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* prevents a potential impact of the selection bias due to differing baseline or confounding characteristics of the subjects;
supports the implementation of other means to reduce the risks of bias (such as blinding)
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* supports the implementation of other means to reduce the risks of bias (such as blinding).
  
 
== B. Guidance & Expectations​ ==
 
== B. Guidance & Expectations​ ==
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'''RISK ASSESSMENT'''
 
'''RISK ASSESSMENT'''
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* Is pseudo-randomisation used instead of strongly recommended true randomisation?
 
* Is pseudo-randomisation used instead of strongly recommended true randomisation?
 
* Is there a risk that randomisation is introduced at allocation ​of subjects per experimental groups but is not maintained throughout the study conduct, outcome assessment and data analysis?​​​
 
* Is there a risk that randomisation is introduced at allocation ​of subjects per experimental groups but is not maintained throughout the study conduct, outcome assessment and data analysis?​​​
 +
  
 
'''PLEASE DO NOT FORGET'''
 
'''PLEASE DO NOT FORGET'''
* To consider adding this subject to a training program for new employees or refresher training (if appropriate)
+
 
 +
* To consider adding this subject to a training program for new employees or refresher training (if appropriate)
 +
* To assess the risks of cross-contamination when animals housed in the same cage are exposed to different pharmacological treatments
 
* To check whether there are feedback channels installed so that your colleagues can identify, record and report errors and critical incidents related to this subject​ (if appropriate)​
 
* To check whether there are feedback channels installed so that your colleagues can identify, record and report errors and critical incidents related to this subject​ (if appropriate)​
 
  
 
== C. Resources ==
 
== C. Resources ==
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Online tools to support randomisation:
 
Online tools to support randomisation:
  
* NC3Rs’ Experimental Design Assistant - [www.eda.nc3rs.org.uk]
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* [https://www.eda.nc3rs.org.uk NC3Rs’ Experimental Design Assistant]
  
* QuickCalcs - [www.graphpad.com/quickcalcs/randMenu/]
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* [https://www.graphpad.com/quickcalcs/randMenu/ QuickCalcs​]
  
* Sealed Envelope - [https://www.sealedenvelope.com/simple-randomiser/v1/lists​]
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* [https://www.sealedenvelope.com/simple-randomiser/v1/lists Sealed Envelope​]
  
* RandoMice software - [[ https://doi.org/10.1371/journal.pone.0237096 read]] - [[https://github.com/Rve54/RandoMice/releases/ download and install]]
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* RandoMice software - [[https://doi.org/10.1371/journal.pone.0237096 read]] - [[https://github.com/Rve54/RandoMice/releases/ download and install]]
  
  
 
Reading material:
 
Reading material:
  
Handbook of Experimental pharmacology chapter on randomization and blinding [https://link.springer.com/chapter/10.1007/164_2019_279]
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* [https://link.springer.com/chapter/10.1007/164_2019_279 Handbook of Experimental pharmacology chapter on randomization and blinding]
  
  

Latest revision as of 07:34, 4 March 2021

​​​​​​​​​​​​​​​​​​​​​​​A. Background & Definitions

Randomisation is a process of random assignment of experimental units to treatment conditions:

  • occurrence of one event should have no influence on the next event (independence principle);
  • randomisation sequence cannot be based on an easily memorizable and reproducible sequence (randomness principle).

Randomization serves three main purposes:

  • enables the application of statistical tests based on the central limit theorem;
  • prevents a potential impact of the selection bias due to differing baseline or confounding characteristics of the subjects;
  • supports the implementation of other means to reduce the risks of bias (such as blinding).

B. Guidance & Expectations​

Randomisation protocol should describe the following:

  • Type of randomisation (simple / unrestricted, block, stratified, etc.)
  • Block size (if applicable)
  • Stratification variables (if applicable)
  • Tools used for randomisation (including copy of a script if R, SAS or another similar script-based software is used)
  • Reproducibility of the randomisation protocol such as the seed of random number generator (if applicable)
  • Reference to the protocol followed (if applicable)
  • Methods to monitor / detect deviations from the protocol (if any)
  • If a decision is made not to introduce a proper randomisation protocol, the reasons should be discussed in a declaration justifying the decision to use pseudo-randomisation or simple interspersion methods.

RISK ASSESSMENT

  • Is pseudo-randomisation used instead of strongly recommended true randomisation?
  • Is there a risk that randomisation is introduced at allocation ​of subjects per experimental groups but is not maintained throughout the study conduct, outcome assessment and data analysis?​​​


PLEASE DO NOT FORGET

  • To consider adding this subject to a training program for new employees or refresher training (if appropriate)
  • To assess the risks of cross-contamination when animals housed in the same cage are exposed to different pharmacological treatments
  • To check whether there are feedback channels installed so that your colleagues can identify, record and report errors and critical incidents related to this subject​ (if appropriate)​

C. Resources

Guidelines on reporting of randomization (in vivo research):

ARRIVE 2.0 ​​​​

Online tools to support randomisation:


Reading material:



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