Sooner or later – probably sooner – you’re going to run into discrepancies in the records concerning your family. You’ll find conflicting birth dates, or variations in names, or differences in places of death, or two of your cousins will swear that two totally different couples are your great-great-grandparents. You’ll need to be able to evaluate the differences and decide what is most likely to be accurate.

Some points to consider:

Be patient; you don’t have to resolve every discrepancy today. Hasty assumptions are too often wrong. You may not yet have all the information you need – be willing to tolerate ambiguities for the time being, while you continue your research.

Record information exactly, even if it conflicts with what you think you know. If a document gives a date as 1851 when everything else you have says 1855, record the 1851 date exactly as it appears in that document. If you make snap decisions and “correct” documents, then you can’t trust yourself later when you have additional discrepancies to resolve.

Gather more records, if possible. Find your family on every census, not just one. Look for the obituaries of several siblings, not just the one who is your direct ancestor, to see who is named as their mother. Sometimes that results in still more discrepancies to sort out, but often you’ll start to see clear patterns that will help you identify the truth.

This isn’t an election. Just because 63 of your cousins insist on the same thing doesn’t make it so — they may all have copied the same erroneous information from the same sloppy internet pedigree. Give due credit to established belief, but don’t be afraid to conclude otherwise if you have ample documentary reason for doing so.

Records created at the time of an event are usually more accurate than records created later. People forget details over time. A contemporary diary entry is probably more accurate than a reminiscence. An obituary is probably more accurate for death information that just happened than it is for information on a birth that occurred 70 years earlier.

Think about the conditions under which a record was created. 19th century census enumerators didn’t bother to ask people how they spelled their names, so don’t read anything important into that. A distraught widow giving information for her husband’s obituary can very easily make mistakes in the details of her husband’s birthplace or his parents’ names, especially when she wasn’t there for his birth and may never have met his parents.

Would someone have had any reason to “fudge” in creating a record? Did an aging woman want to appear younger than she really was? Could a teenage boy have wanted to appear older than he really was? If a baby came a little too soon after a wedding, might his parents later pretend they were married earlier than they were? A county clerk, on the other hand, would have very little reason to falsify the date on a marriage return or a physician’s report of a birth in the county records.

Consider how innocent errors might have been made. Could a “1” have been incorrectly interpreted as a “7” due to careless handwriting? Could “Jan.” have been misread as “Jun” for the same reason? Write the name “David” in cursive, then look closely at it – depending on how carefully you form your letters, someone else might read your “David” as “Daniel.” Could someone have mistaken the date of a will for the date of death? or the place of burial for the place of death?

Consider calculated dates. Someone may tell a census enumerator or a county clerk that he is 20 years old; the enumerator or clerk makes a quick calculation and writes down a year of birth. If your man was born early in the year, that calculation was probably correct – but if he wasn’t born until quite late in the year, the calculation was probably wrong. And people make mistakes in math all the time.

Check maps. Political boundaries change over time. Did your family come from a part of Germany that is now part of Poland? or of France? Did your family live in Upper Canada at one time and Ontario at a later date – while still living in the same house? Were they living in an American town that kept changing counties as the original county was divided and redivided?

Check calendars. A Quaker date recorded as “6th month” (which avoided the use of the names of pagan gods or Roman emperors) might have been converted to “June” by someone who didn’t realize that at the time the record was made, the year began in March (making the sixth month August, not June). Different parts of Europe and North America made the switch from the Julian to the Gregorian calendar at different times – be sure you know which calendar was being used at the time a record was made, and in the case of secondary records, consider whether someone might have already converted a date from one calendar to another.

Consider language and nicknames. “Theodore,” “Gottlieb,” and “Amadeus” are all exactly the same name, made up of “God” and “love” in different languages – is your discrepancy in name due to a simple translation? Common names have nicknames that you might not recognize at first glance: You know that “Bill” and “Will” are often nicknames for “William,” but do you know that “Patsy” is a common nickname for “Martha,” and that “Daisy” is a common nickname for “Margaret” and “Marguerite”? And it’s quite common to find a man called “Robert W.” on one census and “Walter R.” on another – you may never be sure of which order he preferred to use, but there’s little reason to doubt that these are the same person, all else being the same. Don’t make the mistake of assuming a family had twins named Sarah and Sally just because one child sometimes used her nickname and sometimes her formal name.

Consider the overall quality of a record. Is the clerk’s record sloppy, or neat? Does an online pedigree give specific and complete information for generation after generation, or is it full of gaps and calculated dates and incomplete place names? A sloppy clerk is a careless one; an exacting genealogist (even if she doesn’t list all her sources publicly) takes pride in getting things right.

In short, discrepancies are a simple fact of life for genealogists. Resolving them needs one part creativity (to imagine the possible ways the error might have been made) and two parts logic (to consider all the evidence and arrive at the most rational conclusion). You will not be able to “prove” all genealogical facts with mathematical certainty — instead, you will rely on the “preponderance of the evidence,” or that which is most likely to be true, given all available information. That’s one thing that keeps genealogy from being a mechanical, predictable exercise. Enjoy!