I have built a new idea. To test this method, I applied it to several data sets. Then I would like to say that these data sets are only used to test the performance of the new method.
These data sets are only used to test the performance of the new method.
or
These data sets are used only to test the performance of the new method.
or
These data sets only are used to test the performance of the new method.
Which one is correct? I think the first one is the correct one, but not sure.