My thesis involves experimental study with Wistar puppies. I am dividing the puppies equally in relation to the groups. However I only have 4 mothers and I will use all of their puppies. There is 4 groups, male and females (8 rats per gp). I need, in total, 64 puppies.
Here comes the question, will this be a problem in the statistical analysis? I know that there is a calculation that can be done to assess "the litter effect" in studies of this type. Is 6 mothers good to avoid this effect?
Do you think I should ask for more female mothers? So that the rats are not from the same litter. there is some calculation for this?
Thanks in advance,
Dear Quezia Damaris Jones Severino Vasconcelos , in order to avoid litter bias, if you have 4 experimental groups, you should randomize littermates across the 4 groups. In this way each experimental group will have an equal number of rats from each mother.
Dear Raffaele,
Thank you for your reply. I am already doing that! My concern is that I only have 4 mothers. And if is this will be enough to promote a good randomization to the groups. Should I use more mothers?
Dear Quezia, even with 4 mothers, if you randomize littermates across the experimental groups, litter bias will be avoided.
Best,
Raffaele
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