This applet allows you to specify two groups of a quantitative response (in either stacked or split format) and then produce the randomization distribution. 

On the Mac: In order for the applet to recognize the end of line, you need to copy the data from a plain text file, not a rich text file.  If you are using TextEdit, under Preferences, specify the file type as plain text.  Or if you open the .txt file in a browswer, it should work.  (If it is not working, nothing will happen when you press the OK button.)

Setting Number of repetitions to 1 shows the groups being shuffled. Setting Number of repetitions between 1 and 30 shows the groups as they are formed.  Number of repetitions greater than 30 turns off the animation.

The hypothesized group 1 effect is the "benefit" you assume from being in group one. Nonzero values are subtracted from group one before the data are re-randomized and then added back on to the observations assigned to group one.

You can always view the original data by opening and closing the data entry windows.