the data science process product class product sales in sales - in growth sales by product class rank sales ( -yy ax nx sport sport - sport sport - shoes shoes figure growthsales by product classand rank sales are examples of derived and aggregate measures product sold/total quantity soldtend to outperform models that use the raw numbers (quantity soldas input transforming data certain models require their data to be in certain shape now that you've cleansed and integrated the datathis is the next task you'll performtransforming your data so it takes suitable form for data modeling transforming data relationships between an input variable and an output variable aren' always linear takefor instancea relationship of the form ae bx taking the log of the independent variables simplifies the estimation problem dramatically figure shows how log( linear (yfigure transforming to log makes the relationship between and linear (right)compared with the non-log (left