Normalize

Normalizing data

Normalize the data to convert Y values from different data sets to a common scale. This is useful when the want to compare the shape or position (EC50) of two or more curves, and don't want to be distracted by different maximum and minimum values.

Investigators who analyze dose-response curves commonly normalize the data so all curves begin at 0% and plateau at 100%. If you then fit a sigmoidal dose-response curve to the normalized data, be sure to set the top and bottom plateaus to constant values. If you've defined the top and bottom of the curves by normalizing, you shouldn't ask Prism to fit those parameters.

To normalize, click Analyze and choose Built-in analyses. Then select Normalize from the list of data manipulations to bring up this dialog.

To normalize between 0 and 100%, you must define these baselines. Define zero as the smallest value in each data set, the value in the first row in each data set, or to a value you enter. Define one hundred as the largest value in each data set, the value in the last row in each data set, a value you enter, or the sum of all values in the column. Prism can express the results as fractions or percentages.

Notes:

•	If you have entered replicate values, zero and one hundred percent are defined by the mean of the replicates. It is not possible to normalize each sub column separately.

•	The X values are copied to the results table. They are not normalized.

•	Each SD or SEM is normalized appropriately.

•	If you normalize to the smallest and largest value in the data set, you can remove those values (which would become 0.000 and 1.000) from the results.

The Remove Baseline analysis lets you subtract (or divide) all values by the mean of the first few rows. With some experimental designs, this is a better way to normalize than the choices on the normalize dialog.