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Evaluating Evidence: Books

How do you know a genealogy source is correct? You have to learn to evaluate your evidence. It's not as easy as "this is a good source." But it's not rocket science either!

This post will help you get started evaluating evidence and determining if the information you're using is quality information. It'll do that by using books (real paper books and ebooks) as a detailed example. Books are an easy starting place to learn this skill and an often overlooked beginner's starting place in this digital world.

Determining if genealogy information is right involves learning the tested process of evaluating evidence. This post will:

  • Give you resources to learn the standard for genealogy research.
  • Explain the basic differences between asking "is this source right" and evaluating evidence.
  • Explain how to evaluate evidence found in books, an easy starting place to practice your new skill!
image with text, quote is this source correct, unquote, learn to evaluate evidence

I'm going to start by explaining why you should be using books in genealogy research. That includes why some people turn their nose up at them. This is directly related to evidence evaluation, plus potentially exposes you to sources you haven't considered, yet.

Why Use Books in Genealogy?

So many people begin genealogy today with a site like that they don't realize how many other sources are available for their genealogical research.

Before online genealogy was possible, many beginners relied on books. Books are easier to read than documents, and many are indexed. In many cases, books were available locally or at a major repository when the original records weren't or even when microfilm wasn't.

For more advanced researchers, online research with digital images is a huge improvement because now there is access to images of the original records at home or at many more repositories. That means books of the abstracted records are only helpful if they are faster to access (and then an advanced researcher would use that information to quickly find an image based on what was provided in the book).

Books are still a great option for beginners, though!

A quality book of abstracted records will help a beginner avoid issues reading old and unfamiliar handwriting. It will help by correctly spelling unfamiliar words (making it easier to look them up). A quality book might also include a glossary and most include some explanation of the records which is a huge boon to a beginner.

Basically, if you're newer to genealogy research, start with a quality book of abstracted records before getting an image, even if the image is as easy or easier to get. A quality book will help you learn much faster than just using the original record (you still want to get the original, I'm just saying an experienced researcher can skip the book, a beginner gets advantages from starting with a book even if they don't have to use it to find the record they want).

More and more books are being digitized and made available online. They still have the same advantages as a starting source but with the bonus of being accessible from home.

For those books you have to access at a repository, the digital version may be faster to check if it can be accurately searched.

Ebooks represent a small portion of the genealogy books available, but they may be different books than you would find in your local library or the repositories you are able to visit. Take advantage of both what's online and what's "in print" at a local repository.

If you're looking for access to more genealogy "books," check out the Book Bonanza subscription from This gives you access to Genealogical Publishing Company's ePubs (ebooks) from home. If they have lots of titles that could help your research, this is a great option instead of buying more and more and more books or having to wait to make a trip to a repository that has what you need. Depending on what kind of repositories you have easy access to, the online book subscription might really benefit your research. is a major, long-time genealogy publisher of both how-to titles and abstracted records. I have quite a few titles on my personal bookshelves and have used many of their titles at repositories.

I know this is one more genealogy subscription but I've already written about a great way to save money while still accessing "more" online records. You can use my advice about saving money with a newspaper subscription for the Book Bonanza subscription, too. This advice is basically how to get the most from a short-term subscription instead of having a never-ending subscription that adds up, fast. The post discusses the considerations you need to make before paying for a subscription. They are similar for newspapers or ebooks.

Genealogy Books are a Starting Point

Books are just a starting point, though. A "good" genealogist seeks out the best source available. Books (including ebooks) usually are not the best source. They are often the easiest source to use, and there is nothing wrong with that.

Books are often the easiest source to use, and there's nothing wrong with that.

I see genealogists fall into traps at both ends of this issue. Some find a book and stop there, never seeking out the original record the book used or indicates exists. Other genealogists strive to do great genealogy but refuse to use books because they aren't the best source. This just makes your research harder.

Checking a particular type of source is never "wrong." What makes the difference is what you do next.

Checking a particular type of source is never "wrong." What makes the difference is what you do next.

You found a source, now what?

Detailing what a good genealogist does next is at least an entire post in itself and maybe several. Luckily, there's a tested method genealogists use to do great genealogy. This is the Genealogical Proof Standard or GPS.

Since I first wrote this post, the Board for Certification of Genealogists website has undergone a facelift and that includes making the GPS a bit easier to understand.

This changes what I've written a bit (because what I refer to is no longer on the webpage). Although the new phrasing of the GPS is easier to understand, I want to stick with a bit of the old phrasing as I think it's useful in this particular situation---so when you go the BCG website and see the GPS doesn't use this phrase, you've been warned.

But back to our hypothetical situation where we've found a source and wonder what to do next.

Where are we in the GPS with that situation? Following the GPS is our roadmap to reaching a correct conclusion. That means it is NOT a roadmap for day-to-day research. (My "Brick Wall Solution Roadmap" is a roadmap for day-to-day research, it works seamlessly with the GPS but includes steps for working on a project, not just proving a conclusion. Remember, it's called the Genealogical PROOF Standard for a reason).

We can apply the GPS to a research session with just a little "thinking." The first step of the GPS is about research, the second about citation. It is important to understand the nuances of these two steps within the GPS but that's not the purpose of this post.

For this post, what we're interested in (or where we are along the road) is at the third item. You can find the Genealogical Proof Standard (GPS) on the BCG website (you will probably need to scroll a bit down the page, it's five points).

When I wrote this post, the BCG website referred to the third item as "tests," as in testing the sources and information. Now it says "thorough analysis and correlation." These are the same thing.

People had no idea what kind of "tests" without an explanation. You can Google, "genealogy analysis and correlation." If you Google, "genealogy tests" you probably won't get any useful results.

Why am I going on about semantics? For the purpose of this post, we're talking about testing a source. It's a very clear description of what we need to do next.

So here is where we are, we found a source. Now what? We test our source. Actually, we test the evidence. That's another very important (not just semantic) difference.

Genealogical Sources, Information, and Evidence

Realize that there is a difference between "a source" and "evidence." If you're just getting started with the concept of evaluating or testing, I don't want you to get overwhelmed so I'm not going to go into great detail about this. It is important to know and understand the difference, but if you're just learning, let's not jump to calculus before you learn to multiply.

For those who are ready, a source provides information. We can use information as evidence. We need a specific research question before we can use that information as evidence, though.

Learn more in this QuickLesson about Evidence Analysis from Elizabeth Shown Mills, CGSM's Evidence Explained website. [Really, you need to read this QuickLesson, it's vital information if you want to be a successful genealogist. If you don't want to read it now, save it for later!]

Separating a source from evidence kinda blew my mind the first time I learned it. Honestly, for me, it made everything much simpler because you are dealing with individual pieces of information and evidence for an individual problem rather than seeing a whole source.

Note that this is one of the major differences between how we use evaluation in genealogy versus scholarly history (unless academia has adopted some of the same principals in the last fifteen years, I don't keep up with scholarly history, so I'm not sure). I mention this for those who might have a history background they are trying to apply to genealogy.

What's important: We don't ask, "is this source correct?" That's a very hard to answer question.

Instead: Genealogists evaluate the evidence.

You must understand what is meant by a "source" versus "information" versus "evidence" to correctly understand and apply this concept (it's explained in detail in the QuickLesson I linked to above). These aren't arbitrary words, they have specific meanings.

The Genealogical Proof Standard versus a Research Session

Let's get back to the GPS for a moment.

The GPS is applied to reaching a conclusion. What you read on the BCG website may be more involved than what you'd do after using one book.

Essentially, you perform the first four elements of the GPS throughout the research process but to different degrees. The more experienced you are, the more you apply tests automatically to choose your next step.

A simple example would be finding information on a family and noticing a son was born several years after the father died. Doing the simple math tests the information. You may have done analysis (if all the information was in the one source you are looking at) or correlation (if you had to use the information in one source compared to information in other sources).

This may seem too obvious to be a test. Yet, some genealogists just write down exactly what they find without even thinking about it. Part of testing is common sense.

Part of testing is common sense.

Don't be intimidated. You are most likely doing simple testing, maybe even more complex testing. You can learn more about "analysis and correlation" to improve this skill, but practice is also essential.

As a note, the second item in the GPS is citation. You can't actually complete this item without testing your sources/information/evidence (as appropriate).

I mention this to highlight that the GPS is a roadmap to a conclusion, not a roadmap to a research session. It is not a series of steps, as in perform step one then step two. It's more a checklist to determine if you've done enough to consider your question answered (i.e., reached a conclusion).

To use it as a roadmap to a research session we need to adjust (and this still isn't a series of "do one then two").

  1. research=find the source
  2. cite the source (you probably can't finish this at this point but you can do the bulk of the work, you could probably do the bulk of a citation back in your planning stage, though).
  3. test what you found, analyze, correlate, and think about the source, the information it provides, and the evidence it might provide
  4. address or think about how you will address any conflicts (remember, the GPS is for finished projects, we're talking about a research session, you may need another session to address a conflict just as you may need another session to complete your testing).
  5. take good notes using citations, asking yourself questions; basically, this is what you'll need to eventually write a sound conclusion

These all happen during a research session and not in order. Obviously you need to research before testing and test before addressing conflict (the tests identify conflicts). You may test again, add to your citation, take notes at every point, etc.

Let's get back to the purpose of this post, the testing item.

How Do You Know What to Do Next?

After "testing" you make a decision about what to do based on the tests. In the case of books, the next step is usually finding the original source or a more authoritative source.

You will also need to corroborate the information---does it appear to be correct based on other information (this involves correlating which I described for census records in this post).

There's more to testing, analysis, and correlation, but this gives you the general idea if you've never come across these concepts. Learning more can take your research to another level.

Use books as a clue to lead you to more information or the best source for that information.

Using Books for Genealogical Evidence

Once again, you need to understand the concepts explained in the QuickLesson I linked to above.

With books, it's important to understand the types of sources (see the QuickLesson---I'm not talking about census records or birth records when I say "types of sources," I mean original, derivative, or...Yes, there's a third option if you haven't kept up. If you knew there were original and derivative but can't name the third option, go read the QuickLesson, at least up to the case study).

If you had no idea there was such a thing as an original source versus a derivative source, I'll explain it very simply in terms of evaluating books. You can read the QuickLesson later (this is a case of a little knowledge being dangerous but no knowledge being safer since you won't make incorrect assumptions).

Most books are derivative sources. They are not the original source. There are several main issues with books that are derivative sources.

Because books of abstracted/transcribed records had to be copied, there is a greater chance they contain errors (think typos) than a photographic copy such as a photocopy, microfilm copy, or digitized copy. Photographic copies are technically derivatives but we treat them as originals in many cases since they lack many of the problems of other derivative sources.

Another pitfall related to derivative sources is completeness. You need to understand what the book includes. You may need to search the original for the information you want if the book only included certain information, certain years, or certain sections. [This is the situation where a photographic copy might not be equivalent to the original.]

There are also books that are the "original," such as county or family histories. These may or may not be "authored narratives," as mentioned in the QuickLesson.

It depends if information is synthesized (family histories usually are, a county history may be compiled so the portion you are using may be the "original" whereas the actual "history" is synthesized. I know, it's not an easy a or b answer, that's why you need to learn to evaluate evidence!).

Sometimes histories contain explicit sources you can check. More often, you should be looking for clues to sources to corroborate the information.

An example would be mention of military service; you should seek a military service record, pension, or similar record. A county history probably did not use one of these as its source, but it provides a clue that such a record could exist.

The major pitfall with histories is they abound with examples of inaccurate or incorrect information. These may be innocent errors or someone's intentional attempt to cover up a fact or make his/her ancestors sound more important.

Verify the information is correct.

You may also be "testing" the history to determine its quality as a source. If we're talking about evaluating evidence, a history may contain information from an unobtainable source (a person now deceased, for example). The history may be the only source for that piece of information. If you can find a source to verify the information, you should, but that's not always possible.

The purpose of testing a source (not one piece of evidence) is to help you determine how likely it is that the unverifiable information is correct. It's like tasting your cooking. You take one taste to determine if the whole thing is good.

Unfortunately, a whole book is not as well represented by one or two "bites" as your grandmother's secret sauce. It's more like testing the edge of a cake or casserole, or worse yet, tasting a piece from one piece of chicken ('cause there's white meat, dark meat---just like a source may contain different types of information). The first (100) time(s) you test, you are pretty far off. Guess what...

experience is the only way to get better!

The Modern Situation with Books

Unfortunately, ebooks and on-demand publishing have made testing a source even more vital for books. In the past, many books (but not necessarily family histories) went past an editor before being published. That gave you some confidence that they were quality publications.

Testing and evaluation was still necessary but you could start with some confidence, a real advantage for beginners. Now anyone can "print" a book (or ebook) and put it up for sale.

This still happened some in the past. It was more likely someone privately published a genealogy book than some other subjects. However, it was expensive so no one did it for the money. They did it because they were passionate about genealogy.

Now, creating ebooks or self-publishing can be profitable. It's great genealogy authors can now make some money (before they often wouldn't even break-even). Evaluating a source, especially books, is more vital than ever, though.

A Specific and Tricky Situation (optional reading)

I mention this last item because I've been made aware of a specific situation within one of my research specialties where poor quality genealogy books (books of records, not family histories) are being produced and sold.

This takes time to explain and is the only situation I'm aware of but it could happen with other ebooks or self-published books. Feel free to skip this rather long explanation but I want to make it available if you're concerned about the quality of modern books that can look great without going through a publishing house.

I'm not going to call out this situation by name publicly becuase it's complex and I don't want to get in trouble legally if I misstate anything.

The particular case I'm aware of, the information appears good because it's harvested from quality sources. However, there are intentional exclusions of information but this isn't stated (and no one so far can understand why some information is provided and not other information). There is some plagiarism involved (information is certainly copied but some of it isn't illegal, other information... I don't know).

These books would not have been published by a reputable publishing company in the past. They are sold on Amazon so they are, unfortunately, widely available today. Once again, I think it's great we have more affordable printing options but this is even more reason to learn to evaluate evidence.

Easyily published (and potentially profitable) abstracted records are a very dangerous situation for your research. Luckily, since we're talking about records, you'd have to need those specific records to run into a problem and these aren't records most genealogists will need, which is another reason why I'm not being more specific.

If you evaluate a source, its information, and the evidence it can provide, you are less likely to run into a problem. In most cases, it will be obvious when there's an issue.

You will most often find a source is sloppy, indicating you should be careful using it. You might find information is incomplete, indicating you should look for the rest of the information. You may discover the evidence provided is contradictory. Then you have to be a good genealogist and address the conflict (which can be very simple or involve a lot of research---addressing a conflict does not always mean resolving it so everything agrees, but that's a subject for another post).

The poor quality books I mentioned above are the only case I'm aware of where the abstracting appears to be well done and the information is not obviously incomplete.

Some colleagues discovered it was incomplete by comparing it to the source---which they did not know was the source based on source information in the new book (because that information was not provided). They discovered it because they are experts in this area and the information seemed familiar. Upon comparison, they discovered the information was literally copied from another book of abstracted records but was not complete.

The book the information was copied from made it clear what was included and what wasn't, it was a quality source. The copy did not state this and excluded some of the information included in the source book---note this means the information is copied from a copy, never a good situation.

I am an expert in this area, too, but not so familiar with all the source material to have discovered this problem. That's why it's so tricky. It's one situation where you might evaluate the evidence and have a problem for years and not know it.

The solution in this situation is to seek out the original source. I don't mean the book you didn't know the poor quality book came from. I mean the original records.

This can be tough if you're an Occasional Genealogist. You may simply not have a chance to consult the original for quite a while, even if you intend to. One part of evaluating evidence is deciding if we should go ahead and rely on a source that is derivative when the original is available because it appears to be good quality. This is a matter of efficiency.

You should first seek out original records to find additional information or if you have any qualms about the quality of abstraction/transcription. If a book seems high quality and complete, prioritizing finding the original for it over finding the original of something more suspect or incomplete isn't the best next step.

Genealogy is not a rigorous set of steps. Check the index, check the book, get the original, then check the next source. You make choices based on what appears most appropriate based on your evaluation. You don't hold up research to get an original just because it exists. You only hold up research if it seems absolutely necessary.

Similarly, you don't skip getting sources for inappropriate reasons. An inappropriate reason is "it costs money." Legitimately being unable to afford a record is not the same as refusing to spend anything on records (and you are unlikely to be able to afford everything you are aware of at any given time, that's why you need a plan with a budget).

All of these concepts are related to evaluating evidence. You have to learn whether to trust the evidence provided by a source AND learn what you must do next versus what you could do next as well as making an actual decision. Evaluating evidence leads to all of these (using the evidence or not as well as planning "what next."

The above was originally part of my post about ebooks. In that post you will find the discussion of searching ebooks and the related pitfalls. See that post with links to four free sites for ebooks, one subscription site with ebooks, and two genealogy book stores with ebooks, here.

Let me know what questions you have about testing and evaluating books. This was a world wind approach to a complex subject.

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