What is a Primary Source and a Secondary Source?

In my YouTube video on blog writing style, I talked about the importance of bringing in primary sources to enrich your blog posts (and other writing, like white papers). A viewer asked me if I had any tips on finding good primary sources.

Before I answer that question, we need to take a step back and discuss sources in general. And that brings me to the subject of this blog post. (I also recorded a video on this topic. Scroll to the end if that’s more your jam.)

Here’s what I’m going to discuss below:

  • Why you need good, reliable sources in content marketing
  • How to evaluate a source’s credibility, reliability, and accuracy
  • What is a primary source and a secondary source
  • My go-to place for quickly finding lots of primary and secondary sources about a topic
  • A recent example of how I used primary and secondary sources in a blog post for a client

Why do you need good, reliable sources in content marketing anyway?

You might be thinking, “Heck, I’m writing a blog post about a long-tail keyword phrase for a client that’s ultimately trying to draw in a prospective customer to buy what the client is selling. Why on earth do I need to worry about sources? This isn’t an eleventh-grade English class; I’m not writing an academic paper.”

That’s all true.

But using reliable, accurate sources lends credibility to what you’re writing. Are you trying to create light fluff with generalizations and hazy stats that sound suspect? Or are you trying to create a compelling piece that educates and inspires action of some kind?

This is the biggest problem I have with AI right now—and why I’m not worried about AI coming for my job as a freelance copywriter. AI technology hasn’t evolved anywhere close to what a human can bring to the table. AI simply scans the vastness of content already in existence and, through complex algorithms, culls what it’s been programmed to deem as relevant and salient—and then it spits out a narrative.

But how reliable is AI? Not very, based on what we’re seeing. Yes, it gets a lot of stuff right. It also gets a lot of stuff wrong. And where the heck is it getting the right stuff and wrong stuff from—that’s the thing you need to ask yourself.

And it’s precisely WHY you always need to cite sources in your blog posts, white papers, and ebooks—and it’s your responsibility to evaluate said sources before you include them in the first place.

  • Is the source reputable?
  • Is the source reliable?
  • Does the source have an agenda?
  • If you’re dealing with statistics, are they recent?

The definition of “recent” will vary, depending on the topic. For example, health data is a moving target and is often updated regularly. Always aim to find the most recent data and statistics available.

I’m linking to a media bias chart that I encourage you to check out. It provides an excellent starting point on what media publications and news outlets you should consider using—and avoiding—when doing research and citing sources.

Using reliable, reputable, accurate sources shows the reader that you’ve done your due diligence.

For example, let’s say someone is searching for information on kidney stones. Maybe they recently had one and they want to learn ways to prevent a future stone . . . or what to do if they suspect they have another one.

First, they land on a blog post written in the first person where someone talks about their experience with one kidney stone and their “cure” for preventing any subsequent stones from forming. The cure involves a recipe with herbs that the writer says people should drink once a day if they’ve had a kidney stone. There are no stats or sources for this supposed cure.

But in another article, the writer provides official stats on the prevalence of kidney stones (from a reliable source like The National Institutes of Health), tips for foods to eat and avoid (from the National Kidney Foundation), and an interview from a urologist who regularly treats kidney stones and who offers six tips for preventing them.

See the difference?

OK, so how do you evaluate a source’s credibility, reliability, and accuracy?

This is not the place to attempt to break new ground. Go with the gold standards. (A caveat is that I’m US-based, so I’m writing this from a specific lens in terms of what are considered reliable, credible, and accurate sources.)

Sources I consider credible, reliable, and accurate:

  • Pubs and outlets in the middle column (labeled “neutral) in the media bias chart
  • Official US government statistics and data (e.g., census data, Department of Labor stats on various industries, National Institutes of Health, etc.)
  • Interviews with true subject matter experts (SMEs) in their field. A urologist is an expert in kidney stones, but not brain cancer. And I’m not going to quote SMEs who are considered controversial. During the pandemic, a clutch of MDs had vastly different opinions from the majority of other MDs regarding vaccines. Your job as a copywriter isn’t to stir the pot (unless it is, but that will likely be rare). Again, you don’t want the source you use to get in the way of the information you’re trying to impart.
  • Other reliable primary sources (more on this in a moment)
  • Reliable secondary sources (more on this below)

So what is a primary source and a secondary source?

Don’t let the word “primary” fool you. It doesn’t automatically mean “better” than secondary. Think “original” and “first-hand” when you hear the word primary:

  • Original documents, like the U.S. Constitution, the Declaration of Independence, the Gettysburg Address
  • Original letters and diaries: Letters between John Adams and Thomas Jefferson, letters between John Adams and Abigail Adams, The Diary of Anne Frank, Martin Luther King Jr’s “Letter from a Birmingham Jail”
  • Original video and photos. OK, so we live in an age where deep fake videos are a thing and, of course, it’s easy to manipulate photos. So keep that in mind when looking at contemporary videos and photos. But footage and photos from, say, Woodstock or one of the World Wars—those are all primary sources. The footage people capture of events today on their cell phones is a primary source (think of all the footage we’ve seen over the last several years involving police shootings). Police body cam video would also be a primary source.
  • Interviews with people who can provide first-hand or contemporary accounts of an event or topic. As a copywriter, you’ll likely be interviewing “subject matter experts” or SMEs, as we say in the biz. Your SMEs will often be from your client’s company . . . or a client’s customer (when writing a case study). For example, if you’re doing work for a manufacturing company, you might interview the head engineer on a new product they just released. Or if your client throws a 50th-anniversary party with clients and employees and you’re writing a blog post about the event, you might interview people who attended the party. Again, they’re giving first-hand accounts of the event. While these sorts of interviews are considered primary sources, you always have to ask yourself if the person you’re interviewing is reliable and credible. Think about it this way: five people can witness the same car accident . . . and all will have a slightly different “take,” right? That’s why eyewitness accounts, while compelling, aren’t always reliable, even though they are considered primary sources. (And it’s a great example of why “primary” doesn’t automatically mean “better.”)
    • NERD ALERT: Are you a fan of The Newsroom on HBO? I’m a big Aaron Sorkin fan and love this show. Season 2 deals with this entire topic—primary sources, how you decide if someone is credible, and what happens when a source (or the format it’s presented in) gets manipulated. This is something that’s becoming more problematic in our world, given the rise of deep fake videos.
  • Original research. Again, anyone can produce “research.” You want to look for reputable, reliable research. The gold standard in scientific and academic settings is research published in peer-reviewed journals. And yes, since all research is being conducted by fallible humans, even reputable research in reputable journals can miss at times. Which means mistakes happen. And sometimes research, even in respected places, is retracted. (Here’s a famous example.) So you have to keep that in mind. But my point is . . . if you’re doing an article on vaccines, for example, you’re probably going to want to rely on research from places like JAMA rather than a fringe publication. Unless, again, you’re trying to stir the pot.
  • Official statistics and data. Anyone can spout a statistic. We see that all the time on social media. “The majority of folks believe X.” OK, well, how is “majority” defined, in this case, and where did the statistic originate from? What was the study? Has it been replicated? Peer-reviewed? And yes—it’s really hard for lay people (including me) without any training in statistics or statistical analysis to look at data and draw conclusions. People spend years in school learning how to do this accurately.

I rely on places like government sources for data and stats on things related to health, economics, industry stats (for example, the number of truck drivers in the US), and things like that. Another go-to would be The American Cancer Society for all things related to cancer since its stats are always current and reliable.

Another good source for stats on a wide variety of topics is Statista. It describes itself as “the statistics portal for market data” and offers “insights and facts across 170 industries and 150+ countries.” You can access free statistics, but it also has paid options for unlocking even more. I don’t currently pay—I usually can find what I need from the free database.

What is a secondary source?

A secondary source is only one step removed from a primary source. And it usually relies on and/or refers to the primary source. But it brings in additional insight, interpretation, analysis, research, and commentary.

  • Primary Source: The Diary of a Young Girl by Anne Frank
  • Secondary Source: All About Anne by The Anne Frank House

Again, you have to always consider the reliability and credibility of the secondary source. Because anyone can “write” a secondary source. I could write blog posts about Anne Frank. But the secondary source listed above that’s written by the Anne Frank House Museum is a much better source, given the access it has to original materials and the vast knowledge base its curators and people have.

See the difference?

Your writing will likely have a good mix of primary sources and secondary sources.

For most stuff you write, you’ll likely be interviewing subject matter experts (a primary source), referring to official data and stats (primary sources), and rounding out our research with credible secondary sources (like articles about a specific topic).

What’s my go-to place for quickly finding lots of primary and secondary sources quickly?

English teachers will cringe at what I’m about to say. But my go-to place for doing initial research often is Wikipedia. I don’t recommend linking to Wikipedia as your source. But Wikipedia is a great place to do research because Wikipedia’s articles do a lot of the heavy lifting for you thanks to all the citations within.

If you’ve ever read a piece on Wikipedia, you’ve likely seen the superscript numbers referring to footnotes. Those numbers are hyperlinked, so you click on one, and it brings you to the footnote at the bottom of the page, which is where you’ll find the source information—and those are usually hyperlinked as well. So you can often find reliable primary and secondary sources in those footnotes.

Sure, sometimes links are broken. And yes, some articles have better sources than others. But it gives you a great place to start.

Again, you won’t use Wikipedia AS your source, with very few exceptions. I know in my own personal blogs, I’ve linked to Wikipedia. And I have a memory of a client’s blog where I linked to Wikipedia for a non-serious topic. I can’t recall what the topic was, but I do remember highlighting the fact I was deliberately linking to Wikipedia by saying, “According to our good friend Wikipedia . . . ” (or something to that effect).

But 99% of the time, you’re going to want to link to a solid primary or secondary source.

Here’s a recent example of how I wrote a blog post for a client with a mix of reliable primary and secondary sources

One of my clients does compliance in the transportation space, mainly for trucking companies. For Women’s History Month, the client tasked me with writing a blog post about women truck drivers throughout history.

I started by googling “women truck drivers in history” and “first woman truck driver” and things like that. This brought up some names, including Luella Bates.

And luckily Luella Bates has a Wikipedia page. Score! From that page, I learned about her—and I got links to truly great primary sources, including clips of articles from 1920 where she was interviewed and quoted. Talk about great color for my piece!

(Again, a newspaper clip where a person is quoted would be considered a primary source.)

For another woman, Lillie Drennan, I couldn’t find a Wikipedia page, but the Texas State Historical Association had a whole page dedicated to her. Drennan was the first woman to hold a commercial driver’s license in Texas. That’s a great example of a reliable secondary source.

You can read the finished piece here: Women in Transportation: Celebrating Industry Pioneers.

When it comes to doing research for content marketing, use your best judgment.

The more blog posts, white papers, ebooks, and other marketing content you write, the faster and more adept you’ll become at conducting research. You’ll get a sense of where to go for certain stats and which publications provide the most reliable and accurate info.

When you’re not sure about something, use your best judgment and always err on the side of caution. If a statistic sounds too good to be true—or you can’t easily find its origins—it probably is too good to be true. Don’t be lazy with your stats. (Says someone who is certain she HAS been lazy at some point in the last 20+ years.) Go find one from a reputable source.

Got questions? Ask the Copy Bitch.

That’s me—I’m the Copy Bitch. 🙂 You can browse through more blog posts, visit my YouTube channel (again, the video about this particular topic is below), or ask me a question. Contact me or leave a comment on my YouTube channel.

Happy writing!