Fri July 13, 2012 By: Tanmay K

What is the principle behind step deviation and assumed mean method? What are we actually finding di here?pls. explain the concept?

Expert Reply
Sun July 15, 2012
Answer : In the step deviation method , we minimise our problem by assumed mean method where in we consider the mean of the given variables xi whose frequencies are given. i.e one of the variable is assumed as a assumed mean denoted by A .
After that a table is formed using the formula di= xi - A 
then another table is formed using formula ui = (xi - A) / h , here h is the interval size.
this reduces the problem , where we then form a table of fi ui , here fi is the class interval. 
obtaining the values, we put them in the following formula to find the mean :
mean = A + [ (h /N) * summation  fi ui ]
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