5. Test yourself

Randomisation is used to ensure that the means of each group are identical

We randomise our animals so that they won’t fight so much

True
False
True
False

False. Randomisation can not ensure this. But each experimental unit will have an equal probability of receiving a particular treatment

False. If anything it might increase fighting,particularly in mice.


Randomisation  ensures that each experimental unit has an equal probability of being assigned to a particular treatment group

Randomisation is the only way to avoid bias

True
False
True
False

True. That is the main purpose of randomisation. It helps to avoid bias

False. There are other ways such as blinding


In a randomised block design each block needs to be randomised separately

Blinding is used so that other people can not copy our data

True
False
True
False

True. Blocks are like "mini experiments" with one (or more) of each treatment in each block, separately randomised

False. The purpose is to avoid bias. But we don't really want others to copy our data!


Blinding helps us to avoid unintentionally biasing our results

True
False

Classification variables are ones where treatments can not be assigned at random

True
False
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True. That is the purpose. Bias may be caused quite unconsiously

True. But we can still randomise the order in which the subjects are housed and measurements are made