# Bivariate Densities with N(0,1) Margins

This Monday, in the ACT8595 course, we came back on elliptical distributions and conditional independence (here is an old post on de Finetti’s theorem, and the extension to Hewitt-Savage’s). I have shown simulations, to illustrate those two concepts of dependent variables, but I wanted to spend some time to visualize densities. More specifically what could be the joint density is we assume that margins are $\mathcal{N}(0,1)$ distributions.

• The Bivariate Gaussian distribution

Here, we consider a Gaussian random vector, with margins $\mathcal{N}(0,1)$, and with correlation $r\in[-1,+1]$. This is the standard graph, with elliptical isodensity curves

r=.5
library(mnormt)
S=matrix(c(1,r,r,1),2,2)
f=function(x,y) dmnorm(cbind(x,y),varcov=S)
vx=seq(-3,3,length=201)
vy=seq(-3,3,length=201)
z=outer(vx,vy,f)
set.seed(1)
X=rmnorm(1500,varcov=S)
xhist <- hist(X[,1], plot=FALSE)
yhist <- hist(X[,2], plot=FALSE)
top <- max(c(xhist$density, yhist$density,dnorm(0)))
nf <- layout(matrix(c(2,0,1,3),2,2,byrow=TRUE), c(3,1), c(1,3), TRUE)
par(mar=c(3,3,1,1))
image(vx,vy,z,col=rev(heat.colors(101)))
points(X,cex=.2)
par(mar=c(0,3,1,1))
barplot(xhist$density, axes=FALSE, ylim=c(0, top), space=0,col="light green") lines((density(X[,1])$x-xhist$breaks[1])/diff(xhist$breaks)[1],
dnorm(density(X[,1])$x),col="red") par(mar=c(3,0,1,1)) barplot(yhist$density, axes=FALSE, xlim=c(0, top), space=0,
horiz=TRUE,col="light green")
lines(dnorm(density(X[,2])$x),(density(X[,2])$x-yhist$breaks[1])/ diff(yhist$breaks)[1],col="red")

That was the simple part.

• The Bivariate Student-t distribution

Consider now another elliptical distribution. But we want here to normalize the margins. Thus, instead of a pair $(X,Y)$, we would like to consider the pair $(\Phi^{-1}(T_\nu(X)),\Phi^{-1}(T_\nu(Y)))$, so that the marginal distributions are $\mathcal{N}(0,1)$. The new density is obtained simply since the transformation is a one-to-one increasing transformation. Here, we have

k=3
r=.5
G=function(x) qnorm(pt(x,df=k))
dg=function(x) dt(x,df=k)/dnorm(qnorm(pt(x,df=k)))
Ginv=function(x) qt(pnorm(x),df=k)
S=matrix(c(1,r,r,1),2,2)
f=function(x,y) dmt(cbind(Ginv(x),Ginv(y)),S=S,df=k)/(dg(x)*dg(y))
vx=seq(-3,3,length=201)
vy=seq(-3,3,length=201)
z=outer(vx,vy,f)
set.seed(1)
Z=rmt(1500,S=S,df=k)
X=G(Z)

Because we considered a nonlinear transformation of the margins, the level curves are no longer elliptical. But there is still some kind of symmetry.

• The Exchangeable Case with Conditionally Independent Random Variables

We did consider the case where $X$ and $Y$ with independent random variables, given $\Theta$, and that both variables are exponentially distributed, with parameter $\Theta$. As we’ve seen in class, it might be difficult to visualize that sample, unless we have log scales on both axis. But instead of a log transformation, why not consider a transformation so that margins will be $\mathcal{N}(0,1)$. The only technical problem is that we do not have the (nonconditional) distributions of the margins. Well, we have them, but they are integral based. From a computational point of view, that’s not a bit deal… Computations might take a while, but we can visualize the density using the following code (here, we assume that  is Gamma distributed)

a=.6
b=1
h=.0001
G=function(x) qnorm(ifelse(x<0,0,integrate(function(z) pexp(x,z)*
dgamma(z,a,b),lower=0,upper=Inf)$value)) Ginv=function(x) uniroot(function(z) G(z)-x,lower=-40,upper=1e5)$root
dg=function(x) (Ginv(x+h)-Ginv(x-h))/2/h
H=function(xy) integrate(function(z) dexp(xy[2],z)*dexp(xy[1],z)*
dgamma(z,a,b),lower=0,upper=Inf)\$value
f=function(x,y) H(c(Ginv(x),Ginv(y)))*(dg(x)*dg(y))
vx=seq(-3,3,length=151)
vy=seq(-3,3,length=151)
z=matrix(NA,length(vx),length(vy))
for(i in 1:length(vx)){
for(j in 1:length(vy)){
z[i,j]=f(vx[i],vy[j])}}
set.seed(1)
Theta=rgamma(1500,a,b)
Z=cbind(rexp(1500,Theta),rexp(1500,Theta))
X=cbind(Vectorize(G)(Z[,1]),Vectorize(G)(Z[,2]))

There is a small technical problem, but no big deal.

Here, the joint distribution is quite different. Margins are – one more time – standard Gaussian, but the shape of the joint distribution is quite different, with an asymmetry from the lower (left) tail to the upper (right) tail. More details when we’ll introduce copulas. The only difference will be that the margins will be uniform on the unit interval, and not standard Gaussian.

# Academic Blogging, a Personal Experience

I wanted to get back on two posts (one on Academic Blogging, and one on Twitter for Academics), and to update them based on the discussion that followed the panel (on Thanksgiving), as well as some more recent discussions. All comments are welcome ! [the post is quite long, a pdf version is available from papers.ssrn.com/2398377]

• Introduction

To talk in public, to think in solitude, to read and to hear, to inquire and answer inquiries, is the business of a scholar” (from Johnson (1759)). 250 years after, anyone might think that the business has not changed: academics remain in their ivory tower, but from time to time, they have to leave it, to communicate. Recently, Graham (2004) characterized three channels for scholar communications: publication in peer-reviewed journals, conferences and seminars, and a more informal one, that might be called the “new invisible college“, as in  Halavais (2006), that might be related to a “faculty lounge“, using the expression of  Priem, Piwowar, & Hemminger (2012). This third channel is precisely the one that might be related to blogs.

With Internet (emails, blogs, forums, etc), academics now have new mediums to communicate, either within their own community (and launch participative projects), or outside their community. Academic blogs are one medium, among many others.  As explained in Gregg (2006), “blogs have made scholarly work accessible and accountable to a readership outside the academy“. From an insider’s perspective, blogs seem to be extremely popular, because bloggers are active, sharing links, comments, discussions, etc. In 2007, George Siemens was already enthusiastic: “it’s great to see research-focused academics entering the blog space” (see Siemens (2007)). By that time, it was  clearly not as popular as it could be seven years after.

Social medias can be categorized in eight categories, according to Gu & Widén-Wulff (2010) and  Nicolas & Rowlands (2011): blogs, microblogs, RSS, wikis, tagging, social networks, media sharing, and online documents.  For instance, there is also an emerging form of participatory media, with question and answer services, with Quora, and Stackoverflow. But it won’t be mentioned here (some researchers are extremely active there, but it is very difficult to quantify). In this article, we will get back on more than five years of experience, on a scholar blog.  In the first section, we will get back on definitions, on the context, and the origins of the frekonometrics blog, while it started as one of the few official blogs of researchers at Université de Rennes 1, in France. Then, in the second section, we will study the interplay between a blog and other activities within academia. Then, in a third section, there will be a short discussion about microblogging, and the use of Twitter for academics. And finally, the last section will try to explain why, even after almost six years of experience, an academic blogger might still be enthusiastic.

• The Origins and the Context of the Blog

From a technical point of view, blog is a contracted form of weblog, which is a website made up of ongoing entries, that we will call posts (but might also be called articles). Those posts are published in reverse chronological order: the new material is added to the top of the page, the older materials being automatically archived. So it makes it difficult to follows for infrequent readers. There might be tags and categories, which can be used to distinguish posts related to conference, publications, and teaching, or using dedicated keywords.

• Hosting Platforms and Identity of the Blog

The first blog was launched because the Université de Rennes 1 (I was just recruited there as a professor, not yet tenured) decided in 2007 to have its own blog platform for its researchers. It was officially Arthur Charpentier’s blog. On this platform, blogs were not anonymous, they were based on the credibility of the researcher, and the name of the university was on the front page, almost as large as the name of the researcher.

Being hosted by the university is a dangerous practice, since it is not clear what is allowed, and what is not. For instance, during the first year, there were a lot of discussions about the status of researchers, in France. Being not tenured put me in a delicate situation. Even if the blog became well referenced on search engines very fast, it was not very popular, by that time. Except perhaps among students (mine, but also students in other programs). Students understood the interest of the blog, as a place to discuss and to interact. The blog became and extension of the class. After the formal lecture, in the room, the blog became a place to share additional documents, datasets, computer codes, etc. After two or three years, the blog started to be popular, within my own community (in economics, econometrics and applied mathematics), not only among students. I started to be recognized in conferences, and I wanted to stop having an eponymous blog (coincidence, or not, it was also by the time I moved to Montréal). Having an eponymous academic blog is a common practice, which makes sense since most bloggers tend to identify their blogs, as both personal and professional. All the more within academia, where boundaries between professional, academic and personal life may be difficult to establish, mainly because all those aspects intertwined constantly in the life of scholars.

Again, having a blog hosted by the university might yield delicate situations. Those institutions would like to use blogs as communication tools, and might not appreciate when the blog is use to publish satire of one’s own department. After a few years, I wanted to transfer the blog somewhere else. Using the term introduced by Charlotte Frost, used in  Mewburn & Thomson (2013), I wanted my blog to be – still – some sort of academic blog, but an “outstitutional” blog, more than an institutional one. I decided to host the blog on my personal internet provider’s platform. After almost three years at Université de Rennes1, the freakonometrics adventure started officially.

Several platforms were hosting blogs by that time. Some interesting blogs were hosted by scientific journals (such as The American Scientist or Nature) or societies (in Economics, or Statistics).  But those blogs are somehow institutional. Even if my area of expertise if on the border of social sciences, I decided to migrate to the hypotheses.org platform, a “platform for academic blogs in the humanities and social sciences“. This platform has its own scientific committees, and provides a technical support (not to mention the legal one).

• Influences and the Blogging Community

Freakonometrics became a blog dedicated to econometrics, economics and applied mathematics. As explained in Quiggin (2011a), “with the arguable exception of law, economics is the academic discipline where blogging has been embraced most enthusiastically“. This might explain why there is such an active – and enthusiastic – community (see also Quiggin, (2011b) for a discussion). On the other hand, Halford (2012) said that “the situation within academic blogging seems to be that we are currently a bunch of islands that are vaguely connected but not really arranged into continents and groups. We are all spread out across the digital world with a fragmented network between us.

So, what can we find in this community? Some researchers like to use their name, like Greg Mankiw’s blog for instance (with subtitle “random observations for students of economics“). But most of them prefer to hide themselves behind a short title, like “Confessions of a Supply-Side Liberal” (by Miles Kimball), “The Conscience of a Liberal” (by Paul Krugman), or longer one, like “Statistical Modeling, Causal Inference, and Social Science” (by Andrew Gelman). But hide is probably too strong since the editor is never hidden: we usually find a short bio, including a picture (most of the time), as well as a link to a webpage hosted by some university. Other examples might be “I’m a bandit“, with subtitle “random topics on optimization, probability and statistics. by Sébastien Bubeck“, or “what’s new“,  with subtitle “updates on my research and expository papers, discussion of open problems, and other maths-related topics. by Terence Tao“. Some blogs use puns (it is a feature that one can find on almost any blog: most of them use humour, just to explain that this is just a blog) like “Hyndsight“, “a blog by Rob Hyndman“.

Most of those popular blogs are blogs of well-know academics. Greg Mankin is not only a popular blogger, he is also the author of a standard undergraduate textbook in macroeconomics, and so is John Cochrane, editor of the “Grumpy Economist” blog, also author of a standard graduate textbook in financial economics. There are many other well-known academics, willing to reach new audiences. But John Quiggin claims that his own blog is much more popular than his research (on Australian policy issues), as well as Tyler Cowen (one of the contributor of the “Marginal Revolution” blog).

Another category might be blogs with several contributors, such as the “Monkey Cage” blog, dedicated to political science research. This blog contains contributions from several researchers, such as John Sides, Erik Voeten, Andrew Gelman, Joshua Tucker and Henry Farrell. But all those researchers have their own blogs besides.

To get back on my personal experience, the name freakonometrics was chosen for two reasons. The first one is that is was a common word among the community of researchers in the Economics department at Ecole Polytechnique. Freakonometrics meant using Econometrics techniques to answer real life questions. That might be opposed to Mathematical Econometrics, as it was taught to students. Since it was exactly the aim of the blog (write posts about simple questions, with a quantitative approach) I liked the idea of using it at a blog’s name. The second reason is related to a major influence for most bloggers in Economics. In 2005, University of Chicago economist Steven Levitt and New York Times journalist Stephen Dubner published a collection of “economic” articles, claiming that economics is, at root, the study of incentives. This is how freakonomics.com/blog/ started (the first post was published in September 2005). My blog was more about Econometrics than Economics. So I decided to use the freakonometrics name. But this was not a very good idea. If all bloggers know freakonomics, there is no doubt that the two blogs are unrelated. But unfortunately, outside this community, there is confusion (as I noticed many time while discussing with journalists for instance).

• The Structure of the Blog, and the Contents

A blog is usually seen as chaotic, and unstructured. On the opposite, academia, and Science, are places where everything is supposed to be well ordered. Most undergraduate students can not understand where a professor answer “I have no idea what might happen if we relax that assumption“. An open question is a great source of inspiration for a blogger. It might be a start for a bibliographic survey, or on quick simulations. Thus, the blog “offers a unique space to simultaneously achieve efforts related to research, teaching, and service” as mentioned in Grollman (2014). Technically, as recalled in the introduction, a blog is just a series of entries called “posts“, even if, with several thousand words, some posts might also be called “articles“, as suggested in Cohen (2006).

Those posts might be to start a discussion after an open question in the class, to mention in interesting paper recently discovered, to point out an interesting conference, to provide some codes to generate a graph, to upload datasets used in an article about to be published, to criticize an article read in a newspaper, or just to share an experience. Therefore, “academic blog” is a generic term that includes several different genres, from blogs about academic life to pure research blogs (see Walker (2006) for a discussion), even if most of them are hybrid genres. As analyzed in Luzón (2006), making available personal research is a simple way not only to get feedback, but also to increase visibility, to develop “respect and reputation” (as discussed in Gregg (2009)). As claimed by the committee of hypotheses.org, blogs should be seen a lab books, not a substitute to academic journals (a post is not an article, as we will see in the next section) but more a catalogue of personal thoughts (and possibly some findings).

• Academic Life and Blogging Activities

Traditionnaly, according to Merton (1942), academia was governed by some norms of universalism, communism, disinteresredness, and organized scepticism. More recently,  Ziman (1996) claims, on the contrary, that academia was characterized by inverse norms, of  proprietary, local, local, authoritarian, commissioned and expert norms. Blogging is probbly an answer to this shift. In this section, we will get back on interactions of blogging activity with more conventional academic duties.

Walker (2006) explains that  “blogging allowed us to circumvent the power structure of academica“. Blogs are somewhere between the conversational style of the conference, and the writen style of articles. But blogs are clearly outside those communities, blogs are much more accessible: you do not have to attend a conference, you don’t even have to sign up, and you are usually allowed to participate in the discussion, without belonging to the community (you should if you want to publish a response to a published article). Furthermore, the bureaucratisation of the universities has had “profound effects on the writing of academics” (as discussed in Brett (1991)). More specifically, it is nearly impossible for academics to provided a “public intellectual function” nowadays because it goes “against the grain of the job“. Blogs can be seen as an answer of academic, to regain some freedom of speech. As mentioned in Gordon (1998), tenure positions were initially created precisely to prevent academics from pressures, to grant them a strong freedom of speech. But in the 2010’s, tenure positions exist to pressure those who have only temporary contracts.

• Blog Posts and Academic Articles

A blog entry is usually published without any pressure, with no one too impress, just the idea of working through some ideas and concepts, together, the writer and the reader. Academic articles are going through the peer review process. But it is only a peer-to-peer discussion. All those discussions are usually skipped in the final version, and there is no real place for a discussion, except for some controversial papers, where a discussion can be published. As mentioned in Chatterjee & Biswas (2011), some journals now have forums, but there is no place, otherwise to converse about a publish paper. Blogs can be seen as tools for “post-publication review of papers“. This is actually what happened in 2010, when Science published a paper (Sebastiani & al. (2010)), which was then criticized by several science blogs – about methodological fallacies, before being retracted (see Carmichael (2010) and MacArthur (2011) for a full discussion).

Blog posts offer a space not only to summarize a research paper (written in a codified and strict format), but also to discuss the process and the context of the study. As Gregg (2009) suggests, blogs provide a space “distinct from the parent culture of institutions“. A paper might start with a discussion with a colleague, then additional contributors might join to provide additional expertise. The paper is then written in a codified format, and to please potential reviewers. Those reviewers might ask for substantial changes, done because some co-authors really need a publication to apply for a position. Finally, the paper published might have to connexion at all with the initial discussion. Even if bloggers do not want to share with complete strangers the hidden side of a paper, it might be interesting to emphasize dead-ends, attempts that failed, and how the paper started.

• An Academic Blogger is not a (Science) Journalist

Blogging can revamp the relationship between science and society, simply by making research more comprehensible to others, just like journalists do. There have always been connexions between the two communities: academics, who can understand what exactly is claimed in a research study, and science journalists, who can summarize and explain with less jargon. “Historically, academics have been put in a reactive position, responding to questions from reporters. Blogging places academics in a more proactive position, intervening more effectively in popular debates around the topics they research” as claimed by Jenkins (2008).

• The narrative style of a blog post

There is a stark contrast between the story used in a peer-reviewed paper, and the true, untold, research process. The messy side of a research project, and all the dead-ends might be mentioned, maybe as a quick anecdote, in a conference talk. But for junior researchers, it is not the place to discuss the true story (maybe only the shinny side of it). As mentioned in  Conole (2007), “the blogosphere is offering an alternative style of academic discourse“. A blog post is a place for snippets of the work, more informal, with a completely different style. As climed by Pierre Mounier and Marin Davis (from hypotheses.org) the blog is between the oral and the writen form.

Nevertheless, the tone, or the style of writing, is different from one blog to another one. Post can be writen as a reportage, with a journalistic style (where various sources of information are brought together and synthetised into a story), as a formal or more informal essay (where a story is writen, with opinions), it can be more pedagogical (with a lot of questions) or satirical (see  Mewburn & Thomson (2013) for a detailed comparison, with further examples).

But the time when Karl Sagan was criticized (see e.g. Emanuel (1986)) for mentioning a study in Parade (the  American nationwide Sunday newspaper magazine) before publishing it in Science is now far away. As written in Oreskes & Conway (2011), this has been considered as a”violation of scientific norms“. Similarly, because of its style, some researchers cannot consider a blog post as a serious contribution.

Blogs are not the only place where academics are now visible. Academics are also extremely active on microblog platforms, such as Twitter. Twitter is different from blogs. Not only because of the lengths of the “posts“, but also because it is extremely codified (while blogs are clearly not). If academics can use blogs to educate, they can use Twitter to inform, to make interesting material available to the public.

• From Official Rules to Unofficial Uses

Microblogging, on Twitter, is simple. One has to create an account, on twitter.com, and 160 characters can be used for a short bio, with the possible use of an avatar. It is possible to be active, by tweeting (posting online messages with less than 140 characters), or to passive (and then simply follow some discussions). One can use the search window, and then all the tweets containing that word (or that sentence) will appear. It is also possible to follow some hastags (following the # symbol) such as #overlyhonestmethods, or some people (following the @ symbol) such as @freakonometrics. When following that account, all the tweets (posted under the name @freakonometrics) will appear in the so-called TL (or timeline). I will then have a follower (and of course, I might follow back). On can tweet not only text, but also a picture and html links (that will be automatically shortern). Those are the official rules in Twitter.

If not everyone is on Twitter, important people are; at least in Economics. In January, was organized the annual conference of the American Economic Association, in Philadelphia. This is where the job market for PhD students in Economics takes place. It was extremely active on Twitter (updates where obtained by following frequently the #ASSA2014 hashtag). From my perspective (maybe also the people I follow), it looked like everyone there was on Twitter during that (major) event.

• Live-Tweet in Conferences

Another popular use among academics is to use Twitter for live-tweets. But as mentioned on a lot of blogs, one should be careful about live-tweeting. Live tweeting is supposed to be fun, but stay polite, and respectful, and to use quotation marks as much as possible. Getting back on the so-called Twittergate (see McMillan Cottom (2012) for a complete summary), Aaron Bady, used that interesting image, about Twitter within the academic community “I conjured up the image of an appropriate cantankerous old professor yelling at a bunch of punk tweeters to get off his lawn, like Clint Eastwood in Gran Twittarino”.

Again, to get back on my personal experience, I usually do not live-tweet, I do not feel comfortable with it (I prefer to take notes in my book, even if I might also write a post on my blog later on, and I always ask the speaker if I can quote what he or she said). “Some worried that having someone tweet their insights before they publish might increase the likelihood that they will be scooped by a colleague — although others regarded that notion as slightly paranoid” as mentioned in Kolowich (2012). “The debate over live tweeting at conferences is, in many ways, about control and access: who controls conference space, presentation content, or access to knowledge?” wrote Risam (2012). Beyond those ethical considerations, there is also a more practical reason: in mathematics, it is quite difficult to live-tweet. It is difficult to write equations in Twitter, and to mention a graph without the formal model is useless (or misleading). There might some interest when there are computational issues, to share a nice visualization for instance.

•  Twitter as an Online Faculty Lounge

It is also possible to start discussions on Twitter, but it has to remain a short discussion (to ask for precisions and references). An important issue in Twitter is to speed up connections between scientists. But there is nothing new here. Traditionally, scientists have always interacted with other scientists, in sort of one-to-one interactions, attending seminars, conferences, and discussion with colleagues. Using the words of Priem & al. (2013), “informal conversations have moved out of the faculty lounge to online social media platforms”, such as Twitter. One of the interests is to join somehow a larger “virtual department” with colleagues that are not next door, but who might be far away and in other areas of research. One can even discuss with real people, outside academia. Since I have interests in risk modeling, finance, climate, computer science, mathematics, I can also discuss with people working on stock markets, in insurance companies, in data visualization startups, even journalists. A important point is that it becomes possible to interact with open minded researchers. As mentioned in Fox (2012) – slightly changing the title – “blogging [and micro blogging] changed how economics share ideas”.

The first step in the scientific process is to find ideas, new ideas or concepts to investigate, datasets to describe. Following interesting people on Twitter can be the first step. The final step is to communicate findings and to disseminate. The time when researchers were studying the table of contents of journals to find interesting articles is behind us. When disseminating on a blog, we can share codes, graphs, datasets, links to additional material. On Twitter, we have to deal with the 140 characters constraint, which makes it hard. One idea can be to use a nice visualization, a graph, or a map.

• Institutional Accounts and Outstitutional Ones

Another possible motivation for researchers to be active on Twitter might be for dissemination. Using Twitter can help to reach other researchers, outside the (small) circle of one’s community, as well as journalists, or people working in the industry and for governmental organization, even politics. In a large study, Shuai & al. (2012) proved (following 4,600 papers) that papers mentioned on Twitter are more downloaded, and more cited (see also Eysenbach (2011) for a similar conclusion).

• Blogging After Almost Six Years

After more than five years as an active blogger, I have the same diagnosis as Kotsko (2006), which mentions that blogging is “especially great for academics who would otherwise be quite isolated from other academics with similar interests“.

• A Peaceful Island within Academia

To get back on one of the main personal reason why I am still blogging after almost six years, with enthusiasm, is because it is still a lot of fun. And it is a place that I appreciate all the more that academia is currently a very competitive place. I interact with the blogging community because I want to, while (most of the time) I interact with students and colleagues because I have to.  Blogs are probably the last place where we have a complete freedom. Even not to blog, if we do not want to.

There are currently two important issues in academia, when talking about money: tuition fees rise, and the decrease of public funding for research. Those past years, (undergraduate) students became consumers. And as a professor, I am now the seller in the store. Most of our students are no longer interested by the story behind a model; they want some recipes for their future job. They want to know what to use, and when. And since universities evaluate their professors, they ask students to fill evaluation forms. So professors do everything to get good evaluations. That is a simple and extremely rational game. But the pleasure of teaching is lost, sometimes. And similarly, the less money there is to do some research, the more competition. If there are one or two grants in my field of research, in Québec, I have no more colleagues and friends, I have only competitors. We now have to work on different tasks to add lines on our resume. As mentioned previously, it is difficult to find time just to discover something new, and spend some time investigating (without the insurance of getting a publication out of it).

Compared with those conventional academic activities (teaching, doing so research, writing a referee report, filling a form for a grant, etc) blogging is fun. Within the blogosphere, there is no competition, just motivation and stimulation. One can interact with other bloggers, learn from them, and so far, it is still a pleasure to blog. Some bloggers claim that it is a shame that blogging is not recognized (formally) within academia, but actually, it might be seen as a great opportunity. We do blog because we want to: it is not another required task. So it can still be fun…

The process of research is, indeed, a social activity, where we need to keep – and create – interactions with various researchers, read papers, keep our mind open. On the other hand, blogging is definitively a personal activity: I use my blog as a notebook, to keep traces of ideas, or codes, even graphs and interesting readings. From this perspective, blogging is extremely personal. But it is opened, and anyone can access it. So I use my blog to promote my work, and my scholarship. As Greg (2009), I see academic “blogging as conversational scholarship“. Blog are great to encourage conversation, they are coffee houses, in the sense of the XVIIth Century in England. In blog posts, we connect to other blogs, using comments, reactions, and hyperlinks. But actually, Derek de Solla Price (see Price (1986), cited in Horne (2011)) explained that “the prototype of the modern scientific paper is a social device rather than a technique for accumulating quanta of information“. In that sense, having informal discussions is probably the best way to work, as an academic. This is also the idea of Crane (1989), “the growth of scientific knowledge is a kind of diffusion process in which ideas are transmitted from person to person“. Using blogs, we can develop and connect a network of various people, from PhD students to practitioners in the industry, as well as more experienced academics who might share common interests. The blog is read by students, former students, colleagues, probably the dean, and even sometimes the department secretary.

• A Cost-Benefit Analysis

With a simple cost-benefit utilitarist analysis, one will probably blog if benefits are more important than costs. One component is related to time issue: is blogging costing, or saving time? Academics receive frequently emails, asking for explanations on a technical question (from students, former students, or anyone actually) that will need a detailed email answer. It is possible to consider a “reply to public“, with a blog post. Similarly, while teaching, frequently the same question is asked every a year. From my own experience, the first year, I can write an answer in a blog post, and then, I can integrate it to my notes (blog posts can even be more interesting than lectures notes). I cannot believe that blogging is a waste of time, since I see my blog as a long-term memory. It is also possible to integrate material that cannot be used in notes, such as animations, or videos.

A lot of academics claim that “do not have time to waste blogging” but some of them can write extremely long, detailed (and most of the time, nicely structured) replies. If I write a detailed reply to a specific question (because I found the question interesting), why not share it? Either the answer is wrong (or imprecise), but then someone might post a comment, add a reference, a link, etc, or the answer is correct, and then, why not share it? With blogs, dissemination is immediate, as well as comments and feedback.

A lot of researchers within academia still reject blogs because they’re not serious, and not peer reviewed. Not being serious in the style does not mean that the study is not serious and it can still follow a scientific procedure (this is what we can learn from the Ig Nobels). Furthermore, blogs will be peer reviewed as soon as peers will blog. In blog, comments can even be more constructive than comments one gets from referees in a peer reviewed journal. Blog posts are published on the (open) web, not in some journal so expensive that no one can actually read it. Yes, commenting is not a formal or rigorous as a peer review publication, and having opened comments may contribute to establish quality and credibility of a blog. Having comments from the community is a great benefit.

• Conclusion

With recent changes in academia, blogs are a perfect place to interact outside institutions (universities, societies and journals). Academics can find there not only a place for free speech, but also a place to interact with scholars outside the circle of hyper-specialized colleagues. Anne-Marie Slaughter recently said that “all the disciplines have become more and more specialized and more and more quantitative, making them less and less accessible to the general public” (quoted in Kristof (2014)). Blogs are the missing link from the jargon-based papers to the oversimplifying journalistic articles, between the conventional academic article, the lab notes, and the talk in a seminar. But one should keep in mind that “academic blogging can be an important medium, when it avoids the meta-narcissistic onanism of blogging about how important academic blogging is”, as claimed by Parr (2012).

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