As part of an assignment I have to do a leakage study for a chemical product. We have been provided with data from 8 different batches, with 12 observations from each batch. The observed variable represents concentration levels. The batches are numbered B1 to B7, with batch B1 being the ground truth. Some of the batches from B2 to B7 could have been affected by leakage resulting in an increase in concentration levels. We have to decide which batches could have been affected.
The sample mean and sample standard deviation of each batch is different. Further the samples do not appear to be from normal distribution
The first step I want to do is to apply transformation and check for normality. However I have these doubts:
- Is it correct to pool data from all batches, apply transformations and then test for normality?
- If I handle each batch separately, it might be that different batches require different transformations to achieve normality. How do I proceed in this case?