Category Archives: Resources

The precautionary principle

A good topic for blog posts in our general theme area of “probability” for this week might be the precautionary principle.  This idea, which has legal force in some countries, has several forms: one of them is that “if a proposed action is suspected of causing a risk to the environment, then  those proposing the action need to demonstrate that it does not propose a risk; those opposing the action do not need to demonstrate that it does pose a risk.”

Here is a basic scientific paper on the principle


and a link to an important early consensus statement

Wingspread Statement

The precautionary principle is appealing, but there are some obvious problems with it, for instance: What counts as “demonstrated” absence of harm?  What if our choice is not between “risk” and “safety” but between two courses of action both of which are “risky” in different ways?

You could post about the application of these ideas, and its relation to more probabilistic methods of risk assessment, in any one of several contexts: GMO foods, vaccines, cell phones and brain cancer, climate change…


Blogging theme week 11

This week marks the beginning of the third and final blogging period.  The instructional team has not yet reviewed and fixed the grades for blogging period 2, but simply based on the number of posts it is clear that many of you will need to take advantage of the way the scoring system works to raise your blogging grades in this final period. We had a good discussion about blogging in class last Wednesday and the handout from that session is available here if you missed it.

For this week my suggested theme is “Probability in the Media”.   Find a media item (a news article, a YouTube clip, a web page, whatever) that uses probability in relation to an environmental theme, and analyze the ideas using the concepts that we have discussed in class (conditional probability, payoffs, expectations and so on).

Remember that, as always, the theme is only a suggestion.  You are welcome to post on any relevant topic, including one of the earlier suggested themes.  Here is a list of those:


Scientific American article about probability and medicine

Here’s an article from Scientific American which gives a great review of the material we covered in class yesterday (Unit 3.3) in the context of medical testing.


The reference is
Gigerenzer, Gerd and others. April 2009. “Knowing Your Chances: What Health Stats Really Mean.” Scientific American,   44–53.

The notes for section 3.3 have some quotations from Gigerenzer’s book which is related to this article.

Blogging for week 10

I’m disappointed to see that there are no new posts on the blog this week.  I guess the most likely explanation is that most of the students are waiting until the third and final blogging period to try to raise your grade on the blogging component of the course.  The good news is that the blogging grade is the best score that you achieve in each of the three periods, so that there is still everything to aim for even if things have not gone well with your blogging so far.  On the flip side, the blog contributions make up 35 percent of your overall grade, meaning that quality blogging is vital if you want to succeed in this course.

This Wednesday in class we will run a workshop on blogging.  We’ll review the grading rubric, discuss a sample post, and look at ways to improve it.  Please also remember that you are welcome to discuss your blog posts in office hours at any time.  You may also revise any of your posts for blogging period 2 up until the deadline of Friday midnight; the final version is the one we will use for grading purposes.

As you know, you are free to write on any relevant subject in the blog.  I’ve listed past “theme” posts below.  For a new theme this week, I suggest that you might look at environmental justice.   If this phrase is not familiar, you can Google it, or ask yourself the following question: what one factor about a US community would you think best predicts whether or not it will be the site of a toxic waste dump?   The answer given in this 1987 report was a shocking one.  See also the twenty-year update given in 2007.

From the point of view of this course, the mathematical content of such a post could focus on the probabilistic or statistical techniques needed to show a correlation between the location of toxics facilities and the social/demographic profile of the neighborhood.  You can also ask what is the evidence for causation here (as opposed to correlation), and how relevant causation is to the justice question that these reports raise.

Here are the links to past weeks’ blogging themes.

Regression to the mean

One topic we will address in Unit 3.3 is “regression to the mean”.  That is the statistical fact that if one member of a random series is extreme, the next is most likely going to be closer to the average.

The article below gives an interesting take on this in looking at the chances that the children of successful politicians have to grow up as successful politicians themselves.


Blogging for Week 9

I’m going to keep the proposed theme for week 8 (alternative energy sources) open for another week.  That’s partly because not many people have posted yet, and partly because you haven’t had the opportunity to hear Andrew Gutberlet whose case study presentation had to be postponed because of the weather.  You will get to hear him this Wednesday (March 18th), and I think his talk will suggest several ideas related to this theme.

Remember that the themes are only suggestions.  You can post about any topic that is relevant and interesting.  Read here for details about the Alternative Energy Sources theme.

I expect that the next case study session I conduct (Wednesday March 25th) will be specifically about blogging. Stay tuned for more information about that.  The second blogging assessment period ends on March 27th and the third and final period will begin at that time.


Blogging Theme Week 8

The second blogging period ends on March 27th, that is in four weeks time. As you are thinking about your posts for this period, I’d encourage you to read my post summarizing the results of grading for period 1.  To improve your posts, I’d encourage you contact me, Sara or Kaley and make an appointment to talk in office hours or at another time.  We will be happy to provide advice and suggestions, including specific feedback on your current posts if you ask.

A brief general reminder about blogging requirements: you may post on anything related to the course (the “theme” for the week is only a suggestion), and your postings will be graded according to the rubric that appears in the syllabus,  The rubric involves five grading elements: frequency of posting, mathematical content, thematic content, organization and presentation, references and connections.  Blogging is your only “homework” for this course and a high standard will be expected.

The suggested blogging theme for this week is Alternative Energy Sources. I suggest that you take one possible source of non-fossil-fuel based energy and discuss it from the perspectives of economics (cost), feasibility (how near are we to commercial-level application), energy return on energy invested, plant lifetime, distribution mechanisms, long-term sustainability and so on.  Among the sources you could discuss might be

  • Onshore wind energy
  • Offshore wind energy
  • Solar photovoltaic
  • Solar thermal
  • Geothermal
  • Hydro-electric
  • Nuclear fission
  • Nuclear fusion
  • Space-based photovoltaic
  • Wave energy
  • Tidal energy
  • Biofuels (ethanol, biodiesel)
  • Wood

And you could talk about these from a global perspective, from a national perspective, or specifically with reference to Penn State (Andrew Gutberlet’s presentation will provide a lot of useful information here.)

A good general reference for calculations about renewable energy is   Another is Do the Math.

Remember, you are also welcome to post on any of the earlier themes (or on any other relevant topic).

Slides posted for Peak Oil case study

Hi all

I have posted the slides for today’s case study on Peak Oil.   They are available at

I’ve also had the chance to preview the slides for Andrew Gutberlet’s case study next Wednesday.  If you remember, Andrew is manager of engineering services for Penn State’s Office of Physical Plant, and he will be talking about Penn States greenhouse gas (GHG) reduction objectives, with lots of PSU-specific data.  This looks to be a really interesting presentation.


Darla Lindberg’s slides and contact information

I have uploaded the slides from Professor Darla Lindberg’s presentation this afternoon.  They are available from the link below


At the end of her talk, she mentioned an opportunity to work with her graduate seminar next fall.  If you’d like to contact Professor Lindberg about this, or to ask any follow-up questions, her email address is