I am entering a new era on this blog. I am now recycling post titles. Back in 2020, I wrote a post called Chicken or Egg?  The subject of that post was on the importance of specifying a model before specifying the estimator. The subject of this post is different, but no less important. It is a mistake I have seen countless Ph.D. students make, especially when entering the research arena for the first time.  Conversations with said students usually go something like this:         Student: I think I have an idea for a paper.      ..read more

Introverts are special people. Trust me. I know. I am one. Now, not all introverts are the same. However, one thing that nearly all introverts have in common is the desire to avoid, or at least minimize, interactions. We can only take so much.  I was thinking about interactions this week. Not social ones, but rather econometric ones. Not only did I happen to cover this in class this week, but then I came across this tweet by @StatModeling. It led to a blog post mentioning a recent publication on Covid-19 vaccine effectiveness. I am not interested in this article per se for the ..read more

Who knew that there is a song called No More Tears (Enough is Enough) by Barbra Streisand and Donna Summer? [And, if you are thinking to yourself, "Who are Barbra Streisand and Donna Summer?", just keep it to yourself.] The final part of the lyrics are No more tears No more tears No more tears I've had it, we've had it, you've had it, he's had it No more tears Is enough, is enough, is enough, is enough, is enough, is enough, is enough Unfortunately, Barbra and Donna could have easily been discussing econometrics in this song. Econometrics, to many at least, is synonymous with tears. And, al ..read more

So, it snowed in North Texas over night. There is at least 0.25 inches. Of course, that means all schools are closed for at least today and tomorrow. Likely the day after as well. Seems like a good time to turn on Netflix and write another post. I have wanted to write this one for a while, but it also came up during lecture on Monday. And, that may be the last lecture I give this week. The topic of the lecture was very straightforward: omitted variable bias. All empirical researchers understand omitted variable bias; omission of relevant covariates relegates them to the (composite) error term ..read more

Mark Twain famously quipped, "The report of my death was an exaggeration." As with Twain, reports of #EconTwitter's demise has also been grossly exaggerated. Casein point, an interesting econometric question was posed by Casey Wichman. The question concerned testing hypotheses containing parameters estimated from two different specifications (where one specification is estimated using only a subset of the observations used to estimate the other specification ... but that does not change anything).  Several individuals immediately offered a solution: stacked regression.  Hat tip to ..read more

After 2.5 years as department chair, I have found the mental bandwidth to return to my blog on econometric stuff for applied people. Since it is job market season, and many elevator pitches and job talks are about to given, humor me for a short rant on a topic that has long irked me.  The so-called credibility revolution in economics refers to the focus of most empirical research (by academics at least) on credible identification of the causal effects of some policy or intervention or treatment. Whether this revolution has been mostly harmless or sharp is a matter of perspective, but ..read more

Wow, did that semester last a long time! For today, I am back to one of the activities I love, but for which I have had no time or mental energy: talking with all of you. I hope everyone has survived. I won't ask if anyone thrived. That is not the proper metric. Survival is more than sufficient.  It reminds me of a conversation I have repeatedly with a friend of mine. He has a son the same as age as mine (both sophomores at our local high school). He and I co-coached our boys' soccer and baseball teams when they were little. His son is now trying to be the kicker/punter on our high scho ..read more

This is a week filled with great angst. And, while I don't think a good electoral outcome "saves the republic," it does help stem the tide. And avert more unnecessary deaths. At least for a while. So, here's hoping the will of the people leads to a flip flop in our government.  Our government needs a flip; not necessarily from one party to the other. It needs a flip from those in leadership positions that lack the ability or desire to lead to those that do. If politicians who are willing to and able to lead are concentrated in one party, so be it. If individuals on both sides of the aisl ..read more

To say that difference-in-differences (DID) as a strategy to estimate causal effects has seen a resurgence in the past decade would be an understatement. A search for the term on Google Scholar produces nearly 2,000 hits. In 2020. About 22,000 since 2010. And, to say that I am not much of a fan of DID would also be a bit of an understatement. In case you are curious, I feel this way for two reasons. First, the lack of originality, as suggested by Google Scholar. Admittedly, this is an unfair critique. If it works, then it should be popular. But, I have my suspicions. I also have inner ..read more

It's a question nearly as old as time itself, dating back at least to Aristotle.  "Which came first, the chicken or the egg?" Individuals representing different disciplines have arrived at different answers, or no answer at all. I've been thinking about this ancient question lately, and not for the reasons you might think. It would be easy to link this question to questions of causation that many readers of this blog grapple in their empirical research. Does the egg cause the chicken to exist, or does the chicken cause the egg to exist. I'm sure if Paul is reading this -- y ..read more