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.