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- [Narrator] Welcome to Nobel Conversations.
In this episode, Josh Angrist and Guido Imbens,
sit down with Isaiah Andrews to discuss the key ingredients
in their Nobel-winning collaboration.
Josh and Guido, first, congratulations on the Nobel Prize!
Thank you.
- [Isaiah] The work you did together, particularly the work
on the Local Average Treatment Effect,
or LATE framework
was cited as one of the big reasons you won the prize.
At the same time, you only overlapped at Harvard for a year--
if I'm remembering correctly--
it would be great to hear a bit more
about how you started this collaboration
and what made your working relationship productive.
Are there ways in which you felt like you complimented each other,
what got things started on such a productive trajectory?
Your job talk, as I recall, Guido, it wasn't very interesting
but I think it was a choice-based sampling--
It was. It was. [laughter]
I was a very marginal hire there
because they didn't actually interview me
on the regular job market,
but I think they were very desperate to get someone else
to actually teach their courses.
It was after they had a couple of seminars already
and they're still looking in econometrics,
- so Gary called me and kind of-- - [Josh] Gary Chamberlain?
Gary Chamberlain called me and interviewed me over the telephone.
He said, "Okay, well, why don't you come out
and give a talk?"
- [Josh] I remember this talk a little bit.
I remember the dinner that you and Gary and I had.
I remember not being very excited about your job market paper,
but I saw that Gary was and luckily, Gary's view prevailed...
Yes.
- [Josh] ...and Harvard made you an offer
and I think we started talking to each other pretty pretty soon
after you arrived in the fall of 1990, right?
As I said, I came and I didn't have a very clear agenda.
I was a little intimidated getting there.
But Gary kind of said, "No, you should talk to Josh."
You should go to the labor seminar, kind of see what these people do.
They're doing very interesting things there."
I listened to Gary.
As we did.
As we did in the those days and ever since.
I think it helped that we were neighbors.
We both lived in Harvard's junior faculty housing,
partly because housing costs were very high in Cambridge
relative to our salary, which was very low.
I think it also made a difference,
neither of us came from Cambridge,
so there were a lot of MIT people
who already had their whole networks,
kind of our collaborators.
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- [Josh] Well, I think we figured out
a mode of working together, also.
We had kind of a regular date, so we were neighbors
and we often did our laundry together.
We didn't have laundry machines at our apartments.
But we used to do our laundry and we were talking
and you had a way of fairly systematically,
addressing questions that would come up in our discussions
and the one thing that I was very impressed by,
our early interaction, is you would follow up.
You would write some things down.
Looking back at those days, sort of clearly,
I just had a lot more time to actually think.
I look at my junior colleagues now--
[Guido] You don't have time to think now.
[Josh] No, but for me that is kind of one thing,
but I feel now a lot of my junior colleagues
don't actually have a lot of time to think.
People are just doing so many projects,
and it's actually so hard
and there's so much pressure on people to publish.
I remember spending a lot of time sitting in my office
and thinking, "Wow, what shall I do now?"
[laughter]
But it would give me a lot of time
to actually think about these problems
and trying to figure it them out
and I could actually go to seminars
and then the next day have coffee or lunch with Josh or Gary
and actually talk about those things.
- [Isaiah] You guys weren't actually
at Harvard together all that long,
you started working together pretty quickly.
Were you both in the mindset that you were looking for co-authors,
or looking for a particular type of types of co-authors at the time
or was it more sort of fortuitous than that?
- [Josh] I think we were lucky.
I don't remember that I was looking.
I think, it was more fortuitous.
I said I came in, I'd done my job market paper,
and another paper for my thesis
and I was just very happy to come to Harvard
and suddenly there were all these seminars to go to,
and lots of interesting people to talk to,
but it wasn't a very conscious thing on my part.
Looking back, I think there was a moment for me,
where I was discussing instrumental variables,
potential outcomes, treatment effects with Guido
and we had a pretty good discussion,
but then he also sent me some notes
and the notes were very methodical write-up of our discussion
and what you thought,
we had been concluding in a fairly formal way
and I thought, "Well, that's great."
Talk is cheap, right, but with somebody...
- [Guido] Yeah, but-- - ...really writes out their story.
- [Guido] For me, it really helps writing things down
and I do remember working with Josh
and sitting in my office and writing things out
and you guys have all had the discussions with Gary
where afterwards we need to then sit down
and actually write things up
to figure out exactly what was going on.
I think the other thing we had, Guido,
is we had some very concrete questions
that came from applications.
- [Guido] Yeah.
A lot of econometrics, in my view,
that we were schooled in was about models,
here's a model and what can you say about this model?
I think we were thinking about, here's a particular scenario,
draft eligibility is an instrument for whether you serve in the Army.
What do we learn from that?
- [Guido] That's right.
That's right, and that's sort of where your influence
on the way I do research now is still very clear--
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- [Isaiah] Zooming out a little bit, just thinking about
when you guys started working on this,
when you started working together,
any thoughts for folks
who are just interested in finding productive
co-authors being productive?
I mean, Guido already mentioned the importance of having time,
right, which it is.
It is very easily not to have a lot of time to think--
You definitely have to make time.
That's a great question though, Isaiah,
and I tell my students that
you should pick your co-authors as carefully,
maybe more carefully than you pick your spouse.
You want to find co-authors who,
you have some complementarity
and that's what makes a strong relationship.
You don't want to work with somebody
who sees the world exactly like you
and as much as Guido and I agree about things,
we often disagree about things to this day
and it's fruitful to have those discussions
and we had complimentary skills.
I was very empirical. I'm not really an abstract thinker.
Guido was great at figuring out what the principles were.
Yeah, that's right and I totally agree, kind of [inaudible].
These are incredibly important relationships
and you see a lot of people working together
and not necessarily working very well
and then it's very hard often to get out of this relationship.
A good partnering is a beautiful thing, like a marriage.
It produces wonderful children,
the fruits of the scholarship are potentially wonderful
and they exceed the capacity of the partners to do it on their own
but a bad co-authorship can be very destructive
and time consuming and painful, just like a bad marriage.
Arguments may start about who did what when
and intellectual property type issues,
especially when it when it goes a little sour
and somebody thinks the other party is not pulling their weight.
There's more co-authorship now in economics,
I think that's been documented, much more.
- [Guido] Yes.
There's more teams and there's larger teams
and I think that's great, I love working on teams.
We do work on schools with big teams.
I work often with PI teammates like Parag Pathak and David Autor
and then a team of graduate students,
but I see that the students are not always,
in some ways they're a little too promiscuous,
in my view, in their partnering.
They don't think it through.
It's difficult to think it through.
I think, for me, working with people always has involved
spending a lot of one-on-one time with people,
you need to figure out how they think
and what kind of problems they're interested in
and how they think about these problems,
how they like to write, to make that--
And it takes some maturity on everybody's part.
- Yes. Yes. - [Isaiah] In what sense?
Just in the sense of knowing what's going to work for them,
knowing when things are versus aren't working?
- [Josh] Maturity in the sense of having some judgment
to be able to face it honestly, if it's not going well,
sometimes you have to have some difficult discussions.
Is it worth continuing?
"I was hoping you would do this, and you didn't,"
maybe it turns out there's some feeling
in the other direction, the same way.
And Josh is very good [chuckles]
in the being honest, part from the beginning,
- [Josh] For better or worse.
- [Guido] I would write this stuff and then I remember
the first version of the paper with Rubin,
Josh was in Israel at the time,
Don and I were in Cambridge
and so I would talk with Don regularly,
but Don wasn't really doing much writing in those days,
I would write things and then I would fax them to Josh
and they would come back,
the first page just one big cross, "No,"
second page, one big line, "No"
and that would go for awhile but he still does that.
I sent him the first draft of my Nobel lecture,
and Josh goes, "No, no!"
I've gotten some PDF comments like that from Josh, very helpful.
Omit needless words.
I have few co-authors who are willing to do that.
Especially as you get older, it's harder to put up with that.
I would find it harder now to start working with people who did that
early on in a co-author relationship.
It's also very hard because you need to have enough trust.
Josh, for being willing to be very critical,
he was also willing to admit being wrong.
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- [Josh] But you have to be on the lookout for good partners,
somebody who can help you answer questions
that you can't answer yourself.
I think there's a natural tendency for people to gravitate
to people who are similar in outlook and skills
and that's not as useful.
- [Guido] Josh is right, nowadays it's very tempting
to find people who think about the same problems
you're already thinking about, who think along the same lines
and that may not lead to very novel stuff.
But at the same time finding people
who actually have very different ideas,
it's going to take a lot of time.
Guido, you mentioned in passing how working with Josh
has influenced how you do research,
could you say a little more about that?
I'd also be interested to hear from Josh,
did working with Guido influence the way that you do research?
- [Guido] Nowadays, I'm much more conscious of the fact that,
for me, good economic research
comes out of talking to people doing empirical work,
and it's really not reading econometrica
or the reading the stats journals,
but it's actually talking to people doing empirical work,
going to the empirical seminars.
When I was at Berkeley,
David Carr and Raj Chetty, as colleagues there
and I would talk to them and listen to them,
trying to figure out
how are they solving their problems and other things there
where I'm not really quite happy with the way they're doing things
and trying to look for methodological problems,
where there's some more general solutions possible.
I tried to tell it to my students that I encourage them to work
as research assistants also,
for the people doing empirical work at Stanford.
There was no subbing what I learned while I was in graduate school,
but it really came out of working with Josh,
as well as talking to Gary,
Gary was always encouraging of doing that
and because he done that himself,
he'd worked with on empirical problems with Zvi Griliches
early in his career.
Yeah.
Well, I became more more interested in the econometric theory
through our interaction,
and I think empiricists are often impatient with econometric theory,
partly because empirical work is very time-consuming,
and you may have a sense that something is
convincing and sensible
and you haven't really fully made the case for that,
but you're convinced
and that motivates you to pursue it,
like the draft lottery story.
I was pretty sure that was worth doing
and I came away from working with Guido
seeing that there was the potential to say something
more than just about that particular problem,
and I think over the those early years in the 90s,
our thinking evolved together
that there's actually a framework here,
a way to solve a lot of problems
and I think that that is the power of the LATE framework,
is it answers a lot of questions.
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- [Isaiah] In some sense, did you find that,
email versus facts versus in-person,
the medium mattered to how collaboration went
or they're ways that you felt like
it was the most useful to collaborate?
To me, I think what matters most is,
initially you have a period of--
We needed that initial period,
that was very intense with almost daily interaction
and we also became friends.
You don't develop the kind of friendship, electronically usually
[laughter]
but once you have that foundation you can be pen pals
and we did use email, though it wasn't as useful then
but it worked, we definitely had a lot of faxes.
I still have these faxes, long faxes
and then in the summer, I would come to Cambridge,
usually to the NBR meetings and hang around for a few weeks
and you visited me in Israel.
I visited in Israel.
But yeah, there was good foundation from that that year
and in some sense that was enough.
Nowadays,
I have the co-authors in lots of different places,
but it's always been important
to spend some time with people in the same place,
so you understand how they work, how they think,
even to the point that,
you know when they actually respond,
whether they respond quickly or whether that means,
they're not actually doing anything
or that mean they're thinking hard about a problem
and they just take longer,
but you do need to develop some understanding there.
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- [Isaiah] We've talked about how your collaboration started,
maybe just to step back slightly, were they're sort of features about
the environment at Harvard or in Cambridge, at the time,
which you felt contributed to it?
Coming from Brown,
I felt it was very intimidating place because it clearly was a very, very
impressive set of people.
Zvi Griliches was there, Dale Jorgensen--
Gary, Jerry Hausman, Whitney Newey, sometimes Jamie Robins.
I mean, my view of that in retrospect,
I can't say I loved every minute of every talk
I ever gave in that Workshop,
but that was the highest powered,
that was the group you wanted to reach
and you would get extraordinarily insightful feedback,
even if it wasn't always easy to swallow.
Yeah, and I have for a while,
I would basically give a talk every semester
because we didn't have any money to invite people.
Gary would say, "Well, why don't you give a talk?"
[laughter]
That was the arena for young people with our interest.
- [Guido] Yeah, it was really very impressive,
but it was also quite tough--
It was intimidating.
People there had very strong views on what they thought was
the way you should do econometrics,
the way the direction things should go,
now, I would think things were getting a little stale,
that in fact, we were bringing in a lot of the new ideas...
- [Josh] Yeah.
...and that wasn't necessary immediately appreciated.
[laughter]
- [Josh] But that's okay. - And that's fine.
We were pushed and a lot of great discussions
in that workshop about what should we make of LATE
but there were other questions that were just as interesting,
like the role of the propensity score,
that was a big deal in the 90s
and econometrics was moving towards that
and there were a lot of great questions.
Yeah,
I learned a huge amount there from the time I spent--
- [Josh] I think the other thing that Guido and I
both benefited from is we both,
not at the same time, but in early in our careers,
taught econometrics with Gary Chamberlain,
and that was like an apprenticeship for us, I think.
I taught a mixed graduate, undergrad 1126,
I don't know if they still have that number...
- [Isaiah] Mmhmm, they do.
...very interesting course that it had
both graduate and undergraduate enrollment
and it was relatively applied for an econometrics class,
and I learned a lot by teaching that with Gary.
But in that sense, Harvard was a great place,
very flexible there.
The other thing I remember about Harvard is,
well I had very good students,
I taught a lot of wonderful students
who went on to have wonderful careers.
Also, Harvard as an institution,
you're probably are aware of this, Isaiah,
as a junior faculty member, they didn't then ask much of us,
other than teaching our classes.
We didn't have administrative concerns, to speak of.
I think I went to two faculty meetings
in my two years at Harvard
and so we're left--
You were given a lot of freedom and flexibility.
I went to the chair said, "Can I teach this course with Rubin?"
I think it was Friedman at the time. It was like, "Fine."
It wasn't really any concern about what what it was about
and again, that was a very intimidating experience,
but it was a great experience.
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- [Narrator] If you'd like to watch more
Nobel Conversations, click here,
or if you'd like to learn more about econometrics,
check out Josh's "Mastering Econometrics" series.
If you'd like to learn more about Guido, Josh, and Isaiah,
check out the links in the description.
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