False positives confound many paranormal investigation groups. More importantly, a lack of understanding of these phenomena can steadily degrade the reputation of a group and of paranormal research in general.
A false positive "exists when a test incorrectly reports that it has found a result where none really exists." Extending that idea to the paranormal, a false positive occurs when a measurement or recording seems to demonstrate evidence of paranormal activity, yet has a normal explanation.Explanation for the above false positive:A UV light was placed behind the couch to light up the hallway, The family dog comes up from the basement, opens the door and casts a shadow down the hall.
False positives can be in a picture, audio or video clip which instead of containing something paranormal contains normal properties that may be mistaken for something else. Some examples of normal properties that might be mistaken for something else include climatic conditions that produce strange results, bugs flying through the air, a camera strap or hair getting into a picture etc. The most important thing is to always look for logical normal reasons for anomalies and never just assume. Once you have exhausted all possible normal causes for an anomaly then you can say that there is a real possibility that what you have has some paranormal properties to it.