5. Shortcut method to find variance and standard deviation

Shortcut method to find variance and standard deviation:

Shortcut method to find variance and standard deviation Sometimes the values of xi in a discrete distribution or the mid points xi of different classes in a continuous distribution are large and so the calculation of mean and variance becomes tedious and time consuming. By using step-deviation method, it is possible to simplify the procedure.

Let the assumed mean be ‘A’ and the scale be reduced to 1/h times (h being the width of class-intervals). Let the step-deviations or the new values be yi.

i.e