# Normalization results in regression to the mean and inflated Type I error conditional on the reference values

Fig 1C of the Replication Study: Melanoma exosomes educate bone marrow progenitor cells toward a pro-metastatic phenotype through MET uses an odd (to me) three stage normalization procedure for the quantified western blots. The authors compared blot values between a treatment (shMet cells) and a control (shScr cells) using GAPDH to normalize the values. The three stages of the normalization are first, the value for the Antibody levels were normalized by the value of a reference (GAPDH) for each Set.

# Reanalyzing data from Human Gut Microbiota from Autism Spectrum Disorder Promote Behavioral Symptoms in Mice

Update - This post has been updated A very skeletal analysis of Sharon, G., Cruz, N.J., Kang, D.W., Gandal, M.J., Wang, B., Kim, Y.M., Zink, E.M., Casey, C.P., Taylor, B.C., Lane, C.J. and Bramer, L.M., 2019. Human Gut Microbiota from Autism Spectrum Disorder Promote Behavioral Symptoms in Mice. Cell, 177(6), pp.1600-1618. which got some attention on pubpeer. Commenters are questioning the result of Fig1G. It is very hard to infer a p-value from plots like these, where the data are multi-level, regardless of if means and some kind of error bar is presented.

#### R doodles. Some ecology. Some physiology. Much fake data.

Thoughts on R, statistical best practices, and teaching applied statistics to Biology majors.

Jeff Walker, Professor of Biological Sciences

University of Southern Maine, Portland, Maine, United States