What factors contribute to the credibility of a book used as source?

Question

Possibly a very amateur question, yet I think is the best to know the answer as simply and as soon as possible.

Let me use a (not yet IRL, but only hypothetical) example: I want to write either my thesis, possibly even my PhD in the field of video games: construction, psychological relations and so on. I know a man, who's actively working on a successful indie game, and was working on Bioshock games as well - he has a great book in the matter, that is not only easy to read but I found it insightful, too.

What determines, if I'm allowed to use it as a credible resource of game design?

In general, what a resource should qualify to not cause controversies using it in any kind of publication? Or, if the question is too broad, let's focus on a BSc thesis.

Answer 1

It's hard to address the field of video games specifically, since I wasn't actually aware you could do a PhD in that. But broadly speaking, there is some ambiguity with citing books as authoritative sources in professional research since they aren't peer reviewed the way a journal article is. I would look for a few things:

1. Is it canon? In my own field of economics books are frequently cited, but they're often old and seminal. Keynes' General Theory, Smith's Wealth of Nations, and so on. They have essentially been de facto peer reviewed over the course of time. Did, I don't know, Sid Meier write a book?
2. Is the author peer reviewed? Citing a book by an established academic may lend even their non-peer reviewed work sufficient credibility.
3. Is the book based on peer reviewed work? It's not unusual for a journal article to be expanded into a book, or even in some cases for a portion of a book to turn into a journal article. This is true of the General Theory, and more recently Thomas Piketty's Capital. Obviously you should cite the peer reviewed work instead if possible, but it would still help the case of the book portions.
4. Is the author prominent in the field? If you want to cite, for example, George Akerlof's 2015 book in your research, the fact that he's a famous economist with a Nobel prize lends it credibility.

The last point may be particularly relevant for the field of video games, where I suspect the first three will be harder to meet. Unless there's a more robust peer-reviewed network of video game journals than I'm aware of, which is certainly possible. You say this person has some experience in the field, but it's not clear to me that amounts to "prominent". Was he a lead designer? Is he a recognized expert on the topic of relevance? If he's only played a normal contributing role as a member of teams doing these things, I'm leaning toward skepticism.

The bottom line: since books aren't peer-reviewed, the credibility of the work needs to be firmly established in some other way. And as @ff524 said in her answer, it's also going to depend on just how central this source is to your argument or results. If it's just background rather than a central supporting piece, you can relax these requirements. The more central it is, the higher the bar should become.

Answer 2

It depends on how you are using the source - what claims you make based on the source.

For example, if you cite the results of some experiment written up in a paper as accepted scientific fact, then that paper should ideally be in a peer-reviewed publication, and be written by someone who is qualified to perform that experiment. (Or it should be something that you can - and have - verified independently yourself.) A blog post written by someone with no credentials in the field, describing an experiment he did, that you cannot replicate, is not a credible source.

On the other hand, if the claim you make is that "one mistake sometimes made by non-professionals studying X is lack of consideration of Y", then it would be perfectly OK to cite that same blog post as evidence that someone studying X failed to consider Y.

To take your example, if you say "Some professional game developers say that X increases user engagement with a game" or "Contributors to Y say that X increased user engagement" and cite the book, that would be fine. On the other hand, if you state "X increases user engagement with games" as a matter of scientific fact, you need to support that with reference to a credible experiment that studies the effect of X on user engagement using science (not just personal experience).