1. How accurately did I observe? What kinds of inaccuracies in percieving could have been caused by the circumstances of the event or issue? (Did it occur quickly? Were there any physical impediments such as my distance from what happened, the time of day, or weather conditions?) What kinds of inaccuracies could have been caused by my state of mind? (Was I tired? Afraid? Distraught? Angry?) What kinds of in accuracies could have been caused by my mood or my attitude toward the issue, the people, the place? Was I predisposed to view the matter one way?
2. Is what I experienced or observed typical of all such cases? Is it possible that it is more the exception than the rule? Were the circumstances unusual enough that it was different from what it would usually be?

If the evidence is from the experience and observation of other people, as (in addition to the questions you would ask of your own experience and observation):

1. Did the person who reported the matter to me experience or observe the matter him/herself? Or was he/she reporting someone else's experiences?
2. Does the reporter's reputation warrant my accepting the report at face value? (Is he/she regarded as a careful observer? Are his/her statements generally accurate and precise?)
3. If more than one person experienced or observed the matter, do their reports agree?

If the evidence is from your research (that is, from an article, book, magazine, journal, television program, the Internet, etc) ask:

1. If the evidence is found in a written source, how reliable is the source? Is it given to the sensational? Is it considered a responsible publication?
2. How careful does the writer seem to be about avoiding unsupported assertions, oversimplifications, sweeping generalizations? How impartial is the writer? (It's only reasonable to be a bit skeptical about a writer with obvious bias, such as the chairwoman of a political party explaining the virtues of her candidate. She may be speaking impartially, but she will be more prone to unconscious one-sidedness)
3. If the source refers to the results of research, does it provide important details? For example, if the research involved interviews, how many people were involved? What was the range of geographical areas, occupations, and ages of those interviewed? What questions were asked? (Not every research project is sufficiently comprehensive to answer the questions it proposes to answer).

It is important to remember that writers may, consciously or unconsciously, include evidence that supports their views and omit any evidence that challenges it. So an source that seems to present an overwhelming case may actually be a "loaded" argument.