Box Cox Power Transformation versus Blom Transformation -IQ


New Member
Hey! I have a question: For my research I had to analyse if the raw score of an test increases during an academic year. I used the gamlss package in R and found a linear increase- by using the box cox power transformation I normalized the data and calculated IQ scores (based in the prior calculated z scores) However, the norming table of the test is based on blom transformed data. how can I normalize the data with the blom transformation in R (or Spss) ? and whats the difference between these two approaches?

any valid answer will be highly appreciated!