The Burden of Proof: The Types Evidence

When researching or evaluating your experience, there will be a question of proof. Most skeptics will want definite proof. As Carl Sagan said, "extraordinary claims require extraordinary proof", which means most people require a high amount of definitive evidence before they began to accept the probability of an event/occurrence. What adds some complexity to the burden of proof is that even definitive proof can be considered invalid by the skeptic. The criteria for valid proof changes from skeptic to skeptic as well as the degree/quality of proof which makes it difficult to present a case.

So what types of proof/evidence are there:

Definitive
2 : authoritative and apparently exhaustive

   Definitive evidence is ideal as it would provide concrete proof that an event has occurred. Such examples of definitive proof would be "Alien" making a public appearance and the public viewing of alien artifacts or biological specimens (without tampering). As of to do there are no examples of definitive proof. All such example have been debunked or consider invalid for consideration. Such evidence that has been brought forth are consider anomalous or unexplainable at this time, and thus considered invalid.

Circumstantial
1: belonging to, consisting in, or dependent on circumstances
3: marked by careful attention to detail : abounding in factual details

Circumstance
1c : a piece of evidence that indicates the probability or improbability of an event (as a crime)
2a : the sum of essential and environmental factors (as of an event or situation)
   The majority of evidence offered falls into circumstantial category. This is based upon the narrative of those with experiences. The details which they provide and accompanied data will result in a level of probability/credibility of their account. This evidence is often dismissed as well since there is "NO" Definitive proof. It seems that the mere fact that there is a percentile chance of occurrence, the incremental percentage of non-occurrence weighs more to most. So although we can say the is an 80% chance that your story is factual and true, skeptics will point out that there is a 20% margin of error and since within that 20% there are definitive explanation of why the occurrence is not what is claimed.

Corroborative
1: to support with evidence or authority : make more certain

  Going hand in hand with the circumstantial evidence is corroborative evidence. If you find others who can independently support your narrative of the events, there is a better chance of credibility and validity. Other witnesses or experiencees can add to the level of the claim. In addition a person professional and social standing are a factor in this too. Often we consider those in authority or governmental positions to have more credibility, than those of an average person. Likewise a certified individual of a particular field of study is considered to have a higher value of credibility than that of an average person.
  Unfortunately within our modern age we have found that Corroborative proof can be a risk. Most government official are proven to be outright liars or are unable to reveal factual evidence and thus are evasive. Likewise people in public authority or certified fields likewise suffer from the same issue, due to specified knowledge of their fields of interest (ex a biologist has an understanding for the mechanisms on how life works, but does not make them an individual who can properly comment of the social interaction of life).
In the end, the best that corroborative evidence can do is provide an somewhat objective observer of an event.   

Speculative
1: involving, based on, or constituting intellectual speculation; also : theoretical rather than demonstrable

   Based upon deductive reasoning, most narratives of an experience can fall under speculation. This is because the experience cannot be readily demonstrated or repeated to test. This can be because events are either singular in nature, occur in an unpredictable manner, we do not have the ability to test such claims adequately due to limitations of our technology, or the preventive measures of the individuals initiating the encounters.

   So going into this research, the burden of proof is high and criteria for accepted valid evidence is very high and specific. Most of the evidence that will be collected is based upon a narrative, circumstantial evidence, corroborative evidence, and speculation. Any artifacts or material evidence that occurs will most likely be considered an anomalous or at this time is unexplained. Hopefully as our level of technology and knowledge increases over time we can revisit the date we have collected.

   There is already a variety of evidence out there. The number of claims that people have made over the decades, the narratives that people have provided in myths, legends, and past accounts, unexplained geoglyphs and various cultural anomalies, radar records, recovered implants, etc.
Additionally this research can lead to answers and help, in identifying other concrete explanations. It may identify a potential biological/psychological disorder that can be treated with medication/therapy. Explain environmental factors and conditions that may be a relief since these can be explained and corrected.

Anecdotal2:  based on or consisting of reports or observations of usually unscientific observers

The majority of evidence will be the experience of the event itself. Many of those who are witnessing or going through the event can give their testimony. Many are just regular people with various levels of intelligence, maturity, psychological stability,  reasoning, and logic. Many are in a rather emotional state and are unable to give accurate reports, as fear or anger take control.