Well, you can follow the methodologies perfectly but based upon
   an incorrect hypothesis end up with an incorrect conclusion.
   Well.. not 100% incorrect but rather... misleading. Happens all
   of the time. Perfect math. Perfect methodology. Proper
   procedures. Still wrong yet also scientifically valid. Always
   best to proceed with both eyes and ears open as it were, no
   matter who is telling you something. == This is my favorite
   graphic for that. For me personally, I shoot for "High Accuracy,
   Low precision". It gets near enough to the target. But often you
   find people (not just in the sciences but in other fields as
   well), THINKING they've hit high accuracy, high precision, but
   they really hit LOW accuracy, high precision.