As pointed out by Donald Lines Jacobus, "Very often, the relations of dates determine or negate the possibility of an alleged line of descent, or provide clues which might otherwise elude detection." (a quoted by Greenwood page 9, from Rubincam, Milton. Genealogical Research: Methods and Sources. Washington, D.C.: American Society of Genealogists, 1980). I find that the missing link in most, in fact almost all, genealogical research is a total lack of awareness of relationships and context. Virtually none of the people I come in contact with every day are even aware of things like historical national and state boundaries, wars, depressions, population movements and other sociological forces that not only affect families but determine the location and availability of records.
Blindly copying bad data does not ever make good data and failing to put information obtained into context destroys any possible connections to reality. If I say my ancestor was born in 1895 in Arizona, that has no significance at all, unless I also realize the context of the date. For example, that he was just the right age and in the right place to fight in the Mexican Border Campaign of 1916. (Now how many of you out there even knew there was a Mexican Border Campaign of 1916?) Genealogical research out of context is no research at all.
If you trace your family to Massachusetts, for example, start by reading some history. Get the context of the research so that the dates and places will make sense. Not like one researcher I talked to who insisted that two individuals with similar names were the same person, even though the lived on opposite sides of the state. She had never considered the time period and the difficulty of traveling the few hundred miles between the two locations given for each of the individuals.
Quoting from The Critical Anlysis of Documentary Evidence: Basic Skills in the History Classroom, by Lorence, James J.
The student must be made to understand that an effective assessment of a piece of evidence can only be made against an informed background. Recognizing that a historical document does not exist in a vacuum, the student must inquire into the events surrounding the piece of evidence under consideration and place it in its social, political, and economic context. A concern for context also necessitates an exploration of the background of the witness whose writings are under consideration in the classroom. The instructor should then raise the question of whether contemporary attitudes or the students' own values influence criticism and understanding of the source. The next step should be an intensified focus on the text itself. Careful attention should be devoted to the words, their meanings, and their implications. One good guideline for students is that they accept as historical fact only those particulars that may be confirmed by the testimony of two or more reliable sources.It takes time and effort to move from superficial name gathering into the type of analysis that will produce credible historical genealogical evidence.