One way that might work well, would be to make a copy of the data. Delete all of the negative values in the copied data table. Then add a new column to each data table, called "Negitives Included". In the original table, set all of the rows for the new column to "Yes" and in the copied table, set all of the rows to "No". Then use the Concatenate platform to put the 2 tables together. Then you can run your plots and your statistics from the one table, using a Data Filter or a Local Data Filter to specify which data to use.
Jim