22 October 2014

messy big data

Shout out to Michael Jordan at Berkeley for saying what everyone needs to hear:

"[If] people use data and inferences they can make with the data without any concern about error bars, about heterogeneity, about noisy data, about the sampling pattern, about all the kinds of things that you have to be serious about if you’re an engineer and a statistician—then you will make lots of predictions, and there’s a good chance that you will occasionally solve some real interesting problems. But you will occasionally have some disastrously bad decisions. And you won’t know the difference a priori."

12 October 2014

The Myth of I'm Bad at Math

Here is an outstanding op-ed about how we should try to improve our math ability in America-- certainly not by teaching less math!

"In response to the lackluster high school math performance, some influential voices in American education policy have suggested simply teaching less math -- ... The subtext, of course, is that large numbers of American kids are simply not born with the ability to solve for x."

Thanks to Betsy Blake for sharing this with me!

01 September 2014

Kuratowski's Theorem

It has been more than a year since I've written in my theorem journal, but last week in Wisconsin I learned a theorem that definitely deserves to compel my return to the practice!

A graph is planar if it can be drawn in a plane (two dimensions, ie on a piece of paper) without graph edges crossing.

A subdivision of a graph G=(V,E) is a graph resulting from taking an edge e in E with endpoints u,v in V, introducing a new vertex w, and replacing e with two new edges, one between u,w and one between w,v.

Kuratowski's Theorem states that a graph with a finite number of vertices V and edges E is planar if and only if it does not contain a subgraph that is a subdivision of (1) the completely connected graph on five vertices or (2) the complete bipartite graph on six vertices, three in each partition.

Completely connected graph on five vertices:

Image from mathworld.

Complete bipartite graph on six vertices with 3 in each partition:

Image from mathworld.

29 July 2014

Priya Haji

Two weeks ago I had some very sad news. Priya Haji, the amazing and inspiring cousin of my best friend Sheila Hall, passed away at age 44. She was the co-founder of Save-up, a website to help people pay down debt. Before that she co-founded World of Good, a retail company that sold goods made by artisans around the world and promoted fair trade. While in college she co-founded a community recovery center in East Palo Alto called Free At Last.

Fast company did a great article on Priya.

Here you can read Priya's obituary on techcrunch.com.

Here you can watch Van Jones give a tribute to Priya at a celebration of her life.

Priya was always so fun to be around; she worked so hard and embraced everything so fully. She will live on in all of us if we try to be just a little less hesitant and jump in feet first to helping the people around us.

15 April 2014

far better

Preparing a lecture on robust estimation for my class on Thursday, I ran across this gem:

"Far better an approximate answer to the right question, which is often vague, than an exact answer to the wrong question, which can always be made precise." - John Tukey.

09 April 2014

Math in Computer Science

When I was at Wisconsin for my PhD, I visited two highschool calculus classes to try to show the students how useful math can be in real life. We looked at fourier integrals (integration by parts, and useful for modeling cell phone signals!) and decision statistics (when should the basketball team decide to recruit a player?) and talked about all kinds of jobs and the math that they used. Of course, when it came down to it, the students knew their parents don't use math each day in their jobs-- And even a math diehard like me has to admit that in a regular working day, the majority of jobs don't have math.

But that's why I really liked this article that was shared with me awhile ago by my friend Brian Cobb. It's written by a programmer advocating for more math understanding. As the author says, many people (in this case, the three articles he cites) believe that "from a workaday perspective, math is essentially useless." But the fact is, so many real innovations were driven by changing mathematical models and understandings of applications for programming.

My favorite line, of course: "mathematics is a tool for understanding phenomena in the world: the motion of the planets, the patterns in data, the perception of color, or any of a myriad things in the world"... and isn't that a worthy goal?

20 March 2014


I've never been one to take grades extremely seriously. I enjoyed studying the material that was interesting to me... and it turns out, that's not always what's on the test. However, in college I did get concerned that my good-ish grades were an indicator that I wouldn't be successful in electrical engineering. Thank goodness Professor Don Johnson pointed out a statistic to me way back then, that women drop engineering at a much higher GPA than men do-- I don't remember where he found it, but I vaguely remember it was something like women drop out at average of 3.3 and men at average of 2.3-- a full grade point higher.

Today I read an article about women who leave economics majors starting at A- grades. I wonder what this is today for STEM majors. I also appreciated the article's comments about women considering the whole picture-- in some types of technology and business jobs, it does take longer for a woman to get to the point where you will be treated equally (in terms of position and pay) to her male counterparts. Looking at the correlation between female students' choices and her consequences on the job market-- perhaps an A- female gets treated like a B- male? That would be an interesting study to do.