Transform a Column

When you select Transform a Column from the menubar of the STRATEGY for Windows Spreadsheet, the Column Transformation Form appears.

Choose a type of transformation to perform, indicate the name of the column that will be transformed, and provide a name for the new column. Note that all of your original columns are left intact, and a new column with the transformated data is appended to the worksheet.

Transforming a Y column can sometimes improve the regression by more nearly satisfying the requirement that replicates be bell-shaped. When a Y response is likely to make a response surface that is asymptotic to some boundary then there might be a transformation of the Y column that will make the response surface more like a plane or more nearly parabolic. If so use that transformed Y so that the polynomial model will have a better chance of doing good interpolation.

Similarly, a transformation of one or several X columns may be needed to get a response surface that can be fitted well with a polynomial model.

Here’s a brief description of each of the transformation choices that are available. Note that the transformation choice that you select is applied to every cell in the selected column.

Add a Constant -- To subtract a constant, add the negative of that constant.

Multiply by a Constant -- To divide by a constant, multiply by its reciprocal.

Raise to a Constant Power. The constant can be negative or fractional.

Reciprocal -- Calculate the reciprocal of each entry.

Natural Log (Base e) --Take the natural log (base e) of each entry.

Log Base 10 --Take the log (base 10) of each entry.

Sine -- Take the sine of each entry.

Cosine -- Take the cosine of each entry.

Tangent -- Take the tangent of each entry.

Arctangent -- Take the arctangent of each entry. By using a combination of options you can get almost any trigonometric function.

Transform to -1 to +1 Scale -- Transform the entries to a -1/+1 scale.

Add Two Columns -- To subtract two columns multiply one column by -1 and then add them.

Multiply Two Columns -- To divide one column by another take the reciprocal of one column and then multiply them.

If you select one of the choices that involves a constant and a column name is selected, the screen will show a new textbox for the desired constant.