Category Archives: Publishing

How Long Does It Take to Publish an Academic Book?

My first book with original research just came out. (Amazon even has proof!) This excites me, as you can see from this picture from a couple of weeks ago, when I held it it my hands for the first time:

Part of my elation came from reflecting on just how long I had been working on the project. I thought it might be interesting for younger scholars to get a full perspective, so I am writing out a brief timeline of book-related events here. It might also give a better overview on the origins, thought process, and evolution of a long-form project. There is also going to be a healthy dose of luck. And regardless of utility to others, it’s going to be cathartic for me.

Here goes:

9/25/2009: Yes, we are starting almost ten years ago. I was in my gap year between undergrad and grad school. Applications were not yet due, but I was set on getting into a program and making international relations research into a career.

Globally, Iran was getting bolder with its nuclear program. President Obama, at a G20 summit, issued a warning:

Iran must comply with U.N. Security Council resolutions and make clear it is willing to meet its responsibilities as a member of the community of nations. We have offered Iran a clear path toward greater international integration if it lives up to its obligations, and that offer stands. But the Iranian government must now demonstrate through deeds its peaceful intentions or be held accountable to international standards and international law.

I remember watching Obama make that speech (which YouTube has preserved for posterity) and thinking that such a bargain would not work. Everything I had read at that point about credibility and commitment problems would suggest so. Why wouldn’t Iran simply take the short-term concessions and continue building a weapon anyway? No paper had constructed that exact expectation yet, and so I thought it would be a straightforward project.

Nevertheless, it would have to go on the backburner. I still needed to revise my existing writing sample and do grad applications.

4/2010: By this point, I had accepted an offer from the University of Rochester. I started fiddling around with modeling Obama’s deal and came to an interesting conclusion. It seemed that compliance was not only reasonable, it was rather easy to obtain. All the proposing country had to do was give concessions commensurate with what the potential proliferator would receive if it had nuclear weapons. The potential proliferator could not profit by breaking the agreement, as doing so would barely change what it was receiving but would cost all of the investment in proliferation. Meanwhile, as long as the potential proliferator could keep threatening to build weapons in the future, the proposer would not have incentive to cut the concessions either.

This project was a lot more interesting than I thought it would be!

8/8/2010: I moved to Rochester and got serious about trying to formalize the idea. The problem was that I had only taken a quarter of game theory before. So the process was … painful, especially in retrospect. I still have an image of my work from way back when:

I can make out some of what I was trying to do there. It is ugly. But I also think this is useful advice for new students. As a first year grad, you are in a very low stakes environment. Trying to do something and doing it poorly still gets you a foothold for later.

In any case, active progress on this was slow for the next couple of years. I had to take some classes to actually figure out what I was doing.

3/9/2012: I watched the previous night’s episode of The Daily Show for no real reason. In a remarkable stroke of luck, it featured an interview with Trita Parsi, an expert on U.S.-Iranian relations. He made some off-the-cuff remarks about Iran’s concerns of future U.S. preventive action. Fleshing out the logic further gave me the basis of Chapter 6 of my book, with an application to the Soviet Union.

9/2012: I made “The Invisible Fist” my second year paper. At the time, this was the biggest barrier for Rochester graduate students, but the idea from three years earlier got me through it.

The major criticism as I circulated the paper was that the model only explained why states should reach an agreement. And while nonproliferation agreements are fairly commonplace, so too are instances of countries developing nuclear weapons. Trying to simultaneously demonstrate that (1) agreements are credible and (2) other bargaining frictions might make states fail to reach a deal anyway was too much for a single article. I began looking for more explanations for bargaining failure beyond the one I had encountered for the Soviet Union.

5/17/2013: My dissertation committee felt that I had found enough other explanations, as I passed my prospectus defense. This was the first time I produced an outline that (more or less) matches what the book would ultimately look like.

12/2014: International Interactions R&R’d an article version of Chapter 6. It would later be published there. Tangible progress!

5/2015: Reading through the quantitative empirics of my book, Brad Smith suggested a better way to estimate nuclear proficiency. This eventually became our 𝜈-CLEAR paper. I would later replace the other measures of nuclear proficiency in the book with 𝜈.

6/10/2015: After two years of grinding through lots of math and writing, I defended my dissertation. Hooray, I became a doctor!

7/14/2015: The Joint Comprehensive Plan of Action—a.k.a. the Iran Deal—is announced. This was could not have been timed any better. Chapter 7 of my book was a theory without a case, only a roundabout discussion of the Iraq War. But the JCPOA nailed everything that the chapter’s theory predicted. I began revising that chapter.

8/2015: I began a postdoc at Stanford. My intention was to use the year to get the dissertation into a book manuscript and talk to publishers. But after six years of thinking about nuclear negotiations and not much else, I was really burned out. I still received excellent feedback on the project during the postdoc, but I set aside almost all of it. The year was productive for me overall, just not on the one dimension I had intended.

10/2015: The JCPOA went into effect. With nuclear negotiations all over the news, I hit the job market at exactly the right time.

7/2016: I moved to Pittsburgh. Remember that Obama speech in front of the G20? In what is a remarkable coincidence that bookends my journey, that summit was just a couple of miles away from where my office is now.

1/2017: I was still burned out. This became a moment of reflection, where I realized that 20 months had passed without making any progress on the manuscript. I convinced myself that if I didn’t get moving, the thing would hang over my head forever and not provide me any value toward a tenure case. So I cracked down and got to work.

3/2017: I sent an email to an editor at Cambridge. He quickly replied, and we set up a meeting at MPSA. Once in Chicago, he liked my pitch and asked to see a draft when I was ready.

5/22/2017: After making some final changes to the manuscript, I sent off a proposal, the introductory chapter, and the main theory chapter to Cambridge.

6/6/2017: My editor wrote back asking for the full manuscript to look over. I did so the next day. One day later, I saw an email notification on my phone that he had responded. I panicked—there is no way that a one-day response could be good news, right? But it was!

You may notice a theme developing here: my editor was fast.

9/6/2017: After three months, the reviewers come back with an R&R. Hooray!

Having published a few articles beforehand, the R&R process was not new to me. But it is an order of magnitude more complicated for book manuscripts. Article reviews are rarely more than a couple of pages. In contrast, I had twelve pages of comments to wade through for the book. This was daunting: a mountain of work and a lengthy road before any of it actually makes noticeable progress to any outside observer. After having gone through almost two years of burn out on the project, this had me slightly worried.

9/12/2017: I developed a solution to the problem that would work. The key for me to maintain focus and appreciate progress was to create a loooooong list of all the practical steps I had to take in revising the manuscript. By the end, I had a catalog of 70 things to do. I put that number on my whiteboard:

I dedicated at least a couple of hours every day to working on the book. Whenever I finished an item, I would go to the whiteboard and knock the number down by one. This gave me some tangible sense of progress even when the work ahead still seemed enormous. It also kept me focused on this project and resist the temptation to work on lower-priority projects that I could finish sooner.

11/28/2017: I sent the revised manuscript back.

1/28/2018: The remaining referee cleared the book. All the hard steps were over!

3/28/2019: I held the real thing in my hand for the first time.

So almost ten years later, I am all done with the project. I cannot describe how satisfying it was to move the book’s computer documents out of the active folder and into the archived folder. I can now finally put all of my effort into the other projects that have been pushed to the sidelines.

But with all of that said, ten years feels like a bargain. Some of that time was pure circumstances: I had to actually learn how to be a political scientist for a good portion of it. I was also an okay writer at the beginning of this, but now I feel that I have a much better grasp of how to communicate ideas.

Nevertheless, some portion of it was my own fault. I could have not put the project on the back burner for more than a year. I suppose if that was the price I had to pay to maintain my own sanity and happiness (and not work on something I was not into at the time), it was a deal well-worth taking.

I was also really, really fortunate with the review process. The first editor I spoke to was receptive of the project, and the reviewers I pulled liked it. Had that not been the case, it is easy to see how a ten year project could have turned into a twelve or thirteen year project. While I hope that future book projects will not last as long, I doubt this part will be as simple the next time around.

In any case, it feels great to finally be done!

Amazon’s Clever Price Discrimination Strategy

Amazon likes to discount books. Here are some examples, starting with Game Theory 101: The Complete Textbook:

gt101

We are only looking at the print prices in this blog post. Originally $13.99, Game Theory 101 is yours for only $11.75.

It’s a similar story for The Rationality of War:

war

Down from $10.54, you can buy The Rationality of War for $9.30.

And finally, here’s Game Theory 101: Bargaining:

bargain

Originally $11.09, Bargaining now sits just under $10.

I suspect the average consumer is pleased to see these discounts. For authors who publish through CreateSpace, however, these discounts are incredibly confusing. We can set the original price. No matter how much Amazon discounts it, they pay us a set amount of money per sale. As such, we also like Amazon’s discounts. In fact, the larger discount is, the happier we are.

The problem is, the discounts are inconsistent. When you initially publish a book, Amazon will always tag it with the list price. Then, after some time and without any warning, Amazon might reduce the price. Or they might not. I have discussed this problem with other authors, and there doesn’t seem to be any explanation for what’s going on.

That said, I now have a theory. Amazon has found a clever form of price discrimination.

What Is Price Discrimination?
The maximum price any of us is willing to pay for a good or service can vary heavily. A lot of Americans will pay $10 or more to see Fifty Shades of Grey. Meanwhile, others may only be willing to pay $1 to see such a movie. We call such a maximum price an individual’s reservation value.

As a business owner, your dream is to charge everyone their reservation value. For example, suppose Fifty Shades’ potential audience consists of two people, one who is willing to pay $10 to see the film and the other who is willing to pay $1. If you could somehow charge the $10 person $10 and the $1 person $1, you would make $11. This makes you the most amount of money possible.

Of course, movie theaters cannot easily distinguish between those high value and low value types. As such, like most businesses, they offer a single blanket price of $10. The $10 person sees the film but the $1 person does not.

Despite the difficulty in price discriminating, businesses try it to varying degrees of success. Student and senior citizen discounts are perfect examples. Both of these groups live off of fixed (and small) incomes. Consequently, as a whole, they are less willing to pay high prices for entertainment. Businesses like movie theaters therefore offer cheaper prices to these groups than to people who tend to have larger disposable incomes.

Airplane flight prices work in a similar way. Vacation travelers are unwilling to pay $1000 for a flight across the United States. In contrast, many business travelers who need to get to New York on short notice are willing. Airlines thus charge relatively cheap prices on flights booked well in advance and massively jack up the prices on the days before takeoff.

Don’t let these discounts fool you. Although they may make it seem like the businesses are acting generously, the discounts exist to maximize profits.

Price Discrimination on Amazon
Broadly, people who publish through CreateSpace fall into one of two categories: vanity authors and what I will call profit makers. Vanity authors write books without the intention to make money. They simply want to “publish” a book so they can say they have. These authors will sell tens of books to friends and family, but their work will never catch on with a larger audience. They give self-publishing a bad name.

Profit makers use CreateSpace because they do not want to hand over a large share of revenue to a traditional publishing house. Vanity is not a concern here. They invest time in writing books and publishing through CreateSpace because they know their works will make a substantial amount of money.

Unfortunately for Amazon, it is very difficult to differentiate between vanity authors and profit makers. Further, there are substantially more vanity authors than profit makers out there. As such, Amazon’s best guess for any new book coming from CreateSpace is that the work is from a vanity author.

This is where I think Amazon’s price discrimination comes into play. Amazon suspects that every new book is vanity. Sales of vanity books do not operate like a normal market. Vanity authors are selling virtually all of their books friends and family. These individuals are willing to spend more money on these books because they know the author. Their reservation price is consequently higher than your average individual. In many cases, it may be substantially higher—a poorly edited vanity book is essentially worthless to the average consumer, but friends and family might be willing to spend $10 or $20 on the book.

If you are Amazon, what incentive do you have to cut the price? Any discount you offer directly hurts your bottom line, and these vanity books are not responding to standard supply and demand factors. Consequently, you don’t have any incentive to discount. The vanity books will be sold to the friends and family and no one else. No discount maximizes your profit.

Of course, Amazon suffers when the book is from a profit maker, not a vanity author. These books respond to supply and demand, so cutting prices by 10% can actually cause more people to buy them. So Amazon might want to reduce the price in these circumstances.

Put yourself in Amazon’s shoes for a moment. You want to discriminate here to maximize your profit. But how?

From my personal experience and discussion with other authors, I think Amazon has figured out a way. They start by offering no discount, under the assumption that the book is from a vanity author. They then wait. And wait and wait and wait. Vanity books will see their sales fall off a cliff after a month or two. Profit making books will see continued sales over the long term. This differentiates the type of book. Amazon thus cuts the price of books that sell, knowing that doing so will lead to even more sales.

To be clear, this is speculation backed up with some non-random observations. Still, I think there is a good chance that price discrimination explains Amazon’s strategy. Although the discounts may seem to be applied randomly, I can’t imagine a company with $88 billion in revenue is doing this without purpose. Price discrimination explains it.

Kindle Unlimited and the Economics of Bundling

Today, Amazon announced Kindle Unlimited, a subscription service for $9.99 per month that gives buyers all-you-can-read access to more than 600,000 books. And it took, oh, five minutes before someone called this the death of publishing.

Calm down. This isn’t the end of publishing—it is a natural extension of market forces and is potentially good for everyone.

Amazon is taking advantage of the economics of bundling—selling multiple products at an identical price regardless of how much the consumer uses each component. Bundles are all over the place; cable TV, Netflix, Spotify, and Microsoft Office are all examples of bundles. These business plans are pervasive because they work, they bring in a lot of money for their providers, and they leave consumers better off as well.

Wait, what!? How is it possible that both providers and consumers are better off by bundling? A while back, I too believed that this was insane and that bundles were a scam to get me to pay more money than I wanted to. (Why should I pay $1 for Home and Gardening when all I want is ESPN?) But then I read up on bundling and understood my folly.

An example will clarify things (and potentially amaze you, as it did for me not too long ago). As usual, I will keep thing simple to illustrate the fundamental logic without getting us bogged down in unnecessarily complicated math. Imagine a world with only two books available for purchase:

Further, let’s assume that there are only two customers in the world. Let’s call them Albert and Barbara. Albert and Barbara have different tastes in books. Albert prefers Hunger Games to Game Theory 101; he would pay at most $4.99 to read Hunger Games but only $1.50 at most for Game Theory 101. Barbara has the opposite preference; she would pay at most $2.25 to read Hunger Games and $3.99 to read Game Theory 101. You might find the following graphical representation more digestible:

BOOKS

Finally, assume that the marginal cost of each book is $0.00. That is, once the book has been written, it costs $0.00 to distribute each book. This is a bit of an exaggeration, but it is close to reality for electronic books. However, it is definitely not true for physical books (printing, shipping, etc.). This distinction will be important later.

With all those preliminaries out of the way, consider how a seller should price those books in a world without bundling. There are two options. First, you can price a book at a low price to capture the entire market share. Second, you can publish the book at a high price; it will sell fewer copies but make more money per unit.

Let’s apply that decision to Hunger Games. Selling at the low price means a cost of $2.25 so that both Albert and Barbara purchase it. (This is because Barbara’s maximum price for it is $2.25). That brings in $4.50 of revenue. Alternatively, you could sell at a high price of $4.99. This ensures that only Albert will buy. But it also brings in $4.99 in revenue, which is more than if you had set a low price. So you would sell Hunger Games for $4.99.

Now consider the price for Game Theory 101. Selling at the low price requires a cost of $1.50 so that both Albert and Barbara purchase it. (This is because Albert’s maximum price for it is $1.50.) That brings in $3.00 of revenue. Alternatively, you could sell at a price of $3.99. Only Barbara would buy it at this price. But it also nets $3.99 in revenue, which is more than if you had set a low price. So you would sell Game Theory 101 for $3.99. (Not coincidentally, if you click on the books above, you will find that they are priced like that in real life.)

Let’s recap the world without bundling. Hunger Games costs $4.99 and Game Theory 101 costs $3.99. The seller brings in $7.98 in revenue. Neither Albert nor Barbara benefit from this arrangement; Albert is paying $4.99 for a book that he values at $4.99, while Barbara is paying $3.99 for a book she values at $3.99.

Now for the magic of bundling. Suppose the seller bundle of both books for $5.99. Who is willing to buy here? Albert values Hunger Games and Game Theory 101 at $4.99 and $1.50 respectively. Thus, he is willing to pay up to $6.49 for the pair. So he will definitely purchase the bundle for $5.99. In fact, he’s much happier than he was before because he internalizing a net gain of $0.50 whereas he had no gain before.

What about Barbara? She was willing to pay respective prices of $2.25 and $3.99. Consequently, she is willing to pay up to $6.24 for the pair. So she will also definitely purchase the bundle for $5.99. And similar to Albert, she is internalizing a net gain of $0.25, up from no gain before.

So Albert and Barbara both win. But so do the producers—rather than bringing in a total of $7.98, the producers now earn $11.98. Every. Body. Wins. (!)

(Yes, I know that Kindle Unlimited costs $9.99 per month. If we added another book to this puzzle, we could get Albert and Barbara to want to pay that price. But that would require more math, and we don’t want more math.)

Why does this work? Bundling has two keys. First, as previewed earlier, the marginal cost of the products must be very small. If they were larger, those costs would make distributing more goods look comparatively less attractive. This would drive up the cost of the bundle and make it less attractive for the consumers, perhaps forcing them to prefer the a la carte pricing. That helps explain why book bundling is just now catching on; electronic books only cost server space whereas physical copies involve UPS.

Second, it helps when customer preferences are negatively correlated. This pushes everyone’s reservation price for the bundle closer together, which in turn makes the producer more likely to want to sell at the bundled price.

Before wrapping up, bundling has an important secondary effect for authors. The main takeaway here is that producers of the materials can make more money through bundling. This gives authors more incentive to create additional materials—an author who would otherwise only make $10,000 from a novel could now make, say, $15,000 instead. So an author on the fence whether to produce the book is more likely to follow through. This further enhances consumer welfare because those buyers can now read a book that would otherwise not exist.

Finally, “producers” here has meant a combination of authors and Amazon. A skeptic might worry that Amazon will end up taking away all of the revenues. That may be an issue in the long run if Amazon becomes a monopoly, but the revenue share is more than fair for now. Indeed, Amazon is giving authors roughly $2 every time a Kindle Unlimited subscriber reads 10% of a book, which is substantial. And with Kindle Unlimited reaching more consumers than a la carte pricing would, writers can earn revenue from a larger share of readers.

If you want to know more about bundling, I highly recommend you read the Marginal Revolution post on the subject.

Calculate Day-of-Week Sales Averages on KDP

For the longest time, KDP aggregated all sales information by week. Now KDP has nice graphical breakdowns of daily sales. Naturally, I wondered if my sales averages differed significantly by the day of the week. I compiled an Excel spreadsheet to give me a quick answer. Apparently the day of the week does not an impact for me, at least not in any significant way.

Still, I figured others would want to know the same information. As such, I did a little bit of extra work on the spreadsheet to make it usable for others. You can download it here. It is very simple to use. Just follow these four steps:

1) Select the tab in Excel that corresponds to the current day of the week. (For example, if today is Tuesday, use the Tuesday tab.)

2) Go to KDP’s sales dashboard. Use one of the pull down menus to open the last 90 days of sales. This will give you the most days to average over.

3) Copy each day of sales from the graph to the spreadsheet. This will require some work because you have to do it manually and need to pay close attention to graph to make sure you are copying down the correct number.

4) Excel will automatically calculate each day of the week’s average sales.

Again, you can download it here. Let me know what you think.

averages

“I Was a Digital Best Seller!”: NY Times’ Bizarrely Misleading Op-Ed

A couple days ago, the New York Times published an op-ed from Tony Horwitz, a Pulitzer Prize winner, chronicling his publishing of BOOM: Oil, Money, Cowboys, Strippers, and the Energy Rush That Could Change America Forever. A Long, Strange Journey Along the Keystone XL Pipeline. Ostensibly, it is the story of how online publishing does not live up to its hype. In reality, it is a parable of someone without good strategic or business sense committing a bunch of mistakes. And the best part: despite a lack of self-awareness, he gets paid off anyway.

To recap the important points from the op-ed, The Global Mail offered Horwitz $15,000 (plus $5,000 for expenses) to write a long-form piece on the Keystone XL pipeline. By the time Horwitz finished, The Global Mail had folded. He thus approached Byliner, who offered to publish the story as a digital book for 33% of the profits and a $2,000 advance. After a month, his book had only sold 800 copies, not enough to pay through the advance. This leads Horwitz to conclude that digital publishing is a failing enterprise.

However, the op-ed is actually a story of Horwitz making a bunch of mistakes and not realizing it. To wit:

1) As far as I can tell, he never signed a contract with The Global Mail. If I were going to spend a large percentage of my year writing a single story with the promise of $15,000 at the end, I would want a legal guarantee to that money precisely because of the issues he encountered.

2) He had a publisher (Byliner) that apparently did nothing for him. With digital publishing so easy now, the only reason to use a publisher is because they will actually do something for you. After all, Amazon will give you 2/3rds of the purchase price if you go it alone. If you are giving half of that to your publisher, you had better be getting a lot back. Instead, the publisher gave him a cover and siphoned off a large chunk of money.

3) He used an incompetent agent to sign the deal with Byliner. A good agent here would make sure the contract forces Byliner to do its job by publicizing the book to warrant its share of the revenue. Apparently there is no such language in the contract. If you are planning on signing a contract without giving it much forethought, why let the agent steal a percentage of your money as well?

4) Okay, #3 is not completely true—Byliner’s publicist “wrote a glowing review of “Boom” on Amazon, the main retailer of Byliner titles.” Amazon’s review policies make it clear that this is a flagrant violation: “Sentiments by or on behalf of a person or company with a financial interest in the product or a directly competing product (including reviews by publishers…)” are not allowed. So Horwitz is openly admitting that he has used false reviews. In the process, he implicates his publisher as well.

5) He thinks that being on the best sellers list for a particular subcategory means that he was selling a lot of copies. For someone with an extensive publishing history, this is remarkably naive. In fact, you can sell a handful of copies and get on these lists; you should not expect to make it rich unless you are on the overall best sellers list.

So we have a publisher that is completely unhelpful and an author who lacks business and strategic sense who are not making much money on a book venture. Does this warrant a New York Times op-ed on how digital publishing is full of false promises? Hardly.

The irony? The New York Times provides great publicity, even if your op-ed is completely wrong. As it stands, the book is #445 on Amazon’s best sellers list and was probably higher a couple of days ago when the story was first published. The real lesson here is that you can be horribly incompetent and still make a lot of money by writing about all of the mistakes you make—as long as you can convince the New York Times that it is the system’s fault, not yours.

This post has been very negative overall, so I feel like I should end on a kinder note. Tony Horwitz may be a fantastic writer. (I don’t know—I’ve never read anything of his. But a Pulitzer is a good indication.) His book on the Keystone pipeline might be great too. (The reviews on Amazon are good, likely even if you take out the fake review(s).) The takeaway point is that you need more than just good writing to succeed in the publishing world. Horwitz showed a lack of good sense here, and these are mistakes that you should avoid making yourself.

Do Book Sales Determine Number of Book Reviews?

In a word, yes.

That is not what I thought I would say when I first considered writing this blog post. Authors frequently complain that a book of theirs has sold very well and yet does not have very many reviews over on Amazon. And, in fact, that is what inspired me to look into this–my Rationality of War has sold better than I expected it to for the past two years or so, yet it still has zero reviews. Perhaps stranger, Game Theory 101: The Basics is by far my best seller, yet Game Theory 101: The Complete Textbook has the most reviews despite selling only a fraction of the copies.

Aside: I’m being intentionally vague about the exact number of sales any particular book has made because that is a part of my contract with Amazon. The graphs that follow will also be unlabeled. Apologies.

I understand that readers choose to review books for different reasons, so we should not expect reviews to be consistent across genres or even otherwise very similar books. But it seems weird that the difference is so big. Right?

Well, I figured doing some math could help out here. One obstacle to doing a large study on this is having data on a large number of books. Outside of New York Times best sellers, we simply do not know much about sales figures. And looking only at NYT best sellers is problematic since they are all very similar–they have all sold a tremendous number of books.

I can provide a partial solution. I have twelve books up on Amazon and have kept extensive sales records on all of them. While twelve is not a huge number, it will still provide a useful picture on the connection between sales and reviews.

My first thought was to plot the number of sales and the number of reviews each book had. This was not particularly helpful:

notlogged

The diagonal line is the OLS “best-fit” line. Sales do increase the number of reviews, but the graph is not particularly meaningful because of the bunching on the left side of the graph. This is common for data of this type. Book sales have an exponential distribution–many, many books only sell a handful of copies while very few sell a substantial amount. My library also follows this distribution.

To solve this problem, I logged my sales figures and recreated the same graph:

loggedsales

Ah, much better. We now see a clear trend: more sales lead to more book reviews, though the expectation becomes murkier for the best selling of books.

It shouldn’t be surprising that more sales lead to more books–more people reading increases the number of potential reviewers, after all. However, I was surprised by just how strong the relationship is: the correlation between logged sales and reviews is .896! (Positive correlation ranges between 0 and 1, so it is difficult to get much higher than this.) Even the unlogged data have a strong correlation of .757. The number of sales really is determining the number of reviews.

TL;DR

  1. Book sales are extremely correlated with book reviews.
  2. Variance in the number of reviews increases as books become better sellers.

gt101

Game Theory 101: The Complete Textbook Update

Two years ago today, I published the first incarnation of Game Theory 101: The Complete Textbook. (It was incomplete back then, heh.) Every summer, I like to go through it and make changes where I can. This time around, I decided to add a new lesson on games with infinite strategy spaces, like Hotelling’s game, second price auctions, and Cournot competition. I have correspondingly added some content to the MOOC version. Videos below.

Initially, I was hesitant to add more material to the textbook because Amazon’s fee increases as the file size of the book increases. Yet, the size of the textbook shrunk because I cut down on unnecessarily wordy sentences. (Switching “is greater than” to “beats” probably chopped off 300 words from the book.)

The optimistic interpretation: Readers now learn more while reading less!

The pessimistic interpretation: I really, really need to work on writing shorter sentences.

 

gt101