Three C’s in Science: Correlation, Confound, and Causation

If you want to irritate a scientist, start a loud conversation about how two things are connected and therefore, you know that one causes the other. 

Two ice cream friends!

Fight Night: Tenure vs. Adjunct Professors

Normal Job: you are offered a contract with a salary and benefits. Usually, you can get fired at almost any time, but you have some legal protections to prevent you being treated terribly.

In academia, things are not so normal. The two extremes are tenure and adjunct. This post is a short explanation of the two types along with links.

First place-Physics!

For the average high school student, the science requirements consist of one of the following sequences:

9^th grade- Biology; 10^th grade- Chemistry; 11^th grade-Physics

or

9^th grade-Earth Science; 10^th grade- Biology; 11^th grade- Chemistry; 12^th grade- Physics

The original order was developed because educators thought it was the easiest way to teach science. Each course requires successively more difficult mathematics. Students could learn Biology more easily than Chemistry or Physics.

Jury of Your Peers

If you ever read a popular science article that references papers, you’ll often see the phrase “peer-reviewed” (http://en.wikipedia.org/wiki/Peer_review) Scientists typically only trust peer-reviewed papers, but sometimes the public will accept papers that haven’t been peer-reviewed. With the internet, any yahoo can post an article online. So what does this phrase mean?

Peer Review is the process by which scientific papers get accepted and how the scientific community works in general. Basically, your work isn't accepted until your peers agree with you.

Scribbling on paper

Quote from a reader: “I've learned that if you ask a physicist a hypothetical question, they will most likely try to give you a real answer. As a result, never ask a physicist a hypothetical unless you're ready for a real explanation and potentially hand-drawn diagrams on napkins. I love you guys.”

A back of the envelope calculation is a rough estimate performed on a random scrap of paper (like the back of an envelope). They are synonymous with physicists. http://en.wikipedia.org/wiki/Back-of-the-envelope_calculation

Let's go through an example of one of these calculations:
Estimate the number of pizzas consumed by all the students at the Northwestern University during one quarter. (Adapted from University of Maryland)

Significant Other

What’s significant in your life?

Regular person: my partner, my job, my friends, etc.

Scientist: hopefully my data

In everyday use, significance means that something is important and meaningful.

For scientists, significance has a very specific definition, which is referred to as statistical significance (http://en.wikipedia.org/wiki/Statistical_significance).

Basically, if I have a result, what are the odds my result occurred from some specific factor versus the odds that my result just occurred by chance. If I'm confident my result came from some effect, then the result is considered significant.

I like free stuff!

Imagine your favorite ice cream shoppe gives away all of their ice cream for free!

They even include the ice cream recipes and their favorite sundae recipes.

But wait, there’s more!

Anyone can add in their favorite sundae recipes or make their own ice cream.

Sound awesome? Yes.

Well guess what, the free  ice cream sundae of software is open source software (tasty analogy, eh?).

So you want to be an indentured servant?

Question: How do I become an indentured servant in this day and age?

Answer: Become a postdoctoral researcher! (post-doc, http://en.wikipedia.org/wiki/Postdoctoral_research)

See also: National Postdoctoral Association (http://www.nationalpostdoc.org/policy/what-is-a-postdoc)

Why do postdocs exist?

 Graduate schools started graduating more PhDs than there were professor positions available. (Note: this is true for the sciences, but not necessarily for other disciplines.)

Proportionality and Disproportionality: Not just words with too many syllables!

This dog’s legs are disproportionately short for his body!

A proportion relates two different objects via size or some other characteristic.

To evaluate a proportion, establish three factors:

1)      The original object/group

2)      The object/group of comparison

3)      The underlying cause/relationship (if any)

Proportions go awry when someone tries to draw an incorrect conclusion from the data.

I hate cats: a mock scientific presentation

If you continually interact with scientists, you will someday end up in the fighting arena of the scientific world, the presentation.

I have heard that non-scientific presentations are completely different. Apparently, in business presentations, the audience actually listens to the whole talk and waits till the end to ask questions.

Scientific presentations are nothing like that.

Below is a fake transcript of a talk including interruptions entitled “I hate cats”. (Many of the fake audience members (AM) are based on real incidents.)

Science is (Sometimes) Subjective!

Imagine eavesdropping on students in a science class, working on a problem set: “Do you know what the right answer is?” “Am I doing this right?” “How do I know if this is working?”

One of the main misconceptions about science is the existence of some mythical “right answer.” In fact, science is very similar to the issues you find in your day-to-day life. Two different groups reach the opposite conclusion with the same information (for examples, see everything the Republican or Democrat parties have ever said). 

 This is how people picture science working.                     What it’s actually like: confusion at every turn.

 All conclusions are categorically “right” or “wrong”.

Paint, Tom Sawyer, and Errors

Today’s post is about the difference between random error (http://en.wikipedia.org/wiki/Random_error) and systematic error (http://en.wikipedia.org/wiki/Systematic_error). Another analogy awaits you. (This blog could probably be entirely about errors.)

Imagine painting a wall. You finish your first coat of paint. Before passing out from the paint fumes, you notice that there are spots missing paint. Furthermore, you notice there seem to be two types of areas without paint.

The Science Inquisition

Memory of your time in K-12 classrooms probably conjures up visions of memorizing facts and regurgitating them for exams.

In particular, science labs often consisted of a box of equipment, a set of instructions, and the correct conclusion. Wrong answers resulted in error analyses and feelings of shame.

Upon venturing into the science education world, I’ve repeatedly heard the words “inquiry” and “inquiry-based learning” (http://en.wikipedia.org/wiki/Inquiry-based_learning).

Inquiry-based learning is very opposite to traditional learning, and science is the subject most conducive to inquiry-based inquiry or open learning. In this type of classroom, there are no right or wrong answers. Students are given the box of equipment with no instructions. They spend class time exploring and then develop questions and theories based on their observations.

Cross Posting!

Hey all,

The Berkeley Science Review posted my original post on numbers as a guest blog post:
http://sciencereview.berkeley.edu/five-hidden-facets-of-numbers/

If you're into repetition, feel free to read it again! There's some other really cool posts on there as well so check them out!

Error Bars, Average Heights, and Pizza

Loyal reader, have you read your research article yet? Perhaps, you've noticed little lines on all the figures and wondered what they are. Those are error bars.

In the first post, I talked about the type of error that arises due to our finite measurements.This post is about another type of error called standard deviation, which basically relates to the spread of a data set.

You take the magic ruler from the first post and attempt to find the average height of Americans. Ignoring sample size, you take two small groups of five people randomly found on the street.

Group 1 Heights: 5’7”, 5’8”, 5’9”, 5’10”, and 5’11”

Group 2 Heights: 5’3”, 5’6”, 5’9”, 6’0”, and 6’3”

How to survive an encounter with a physicist

If you’re reading this blog, there is a high probability that you will encounter a physicist at some point in your life.

Here’s a roadmap to surviving this conversation.

Introduction: If you’re like 99% of the population, you’ll have one of the following two reactions upon meeting a physicist: “Oh, I loved physics in high school!” or “Oh, I hated physics in high school!”

Guess what? We don’t care. Feel free to keep this thought inside your own head.

Note: If you choose to exit at this point, please try to leave politely. Wrong strategy: just walking away (it’s happened).We already have enough rejection in our lives (grants, papers, dating, etc).

Archiving: Not just for Librarians anymore

Scenario 1: You’re 12 years old, and you’ve just discovered a juicy new piece of gossip. You want to be the first to share it with your friends. Unfortunately, you’re stuck in the 1960s so all you can do is try to be the first one at school. Alas, a classmate has beaten you to it!

Flash forward to now. Instead of running to school, you can post the news on Twitter or Facebook. It’s even time-stamped so nobody can dispute that you were the first to know the news.

Scenario 2: You’re a poor struggling graduate student doing research. You have an amazing new discovery that would allow you to graduate once published. You rush to submit your article to a journal.

Disaster strikes! You’ve been scooped! (Someone has published the same result before you.) Three years of your life wasted. If only you could have published your research first. (http://www.phdcomics.com/comics/archive.php?comicid=794)

Solution: The arXiv (http://arxiv.org/)

Erdős, the Kevin Bacon of the Math world

If you hang out with math nerds for an extended period of time, they will inevitably bring up Erdős numbers.

So what is an Erdős number? And what does this have to do with Kevin Bacon?

Most of us are familiar with “Six Degrees of Kevin Bacon”. In this game, you try to connect any actor or actress with Kevin Bacon in the fewest number of steps.

For example, Tilda Swinton was in “Constantine” with Pruitt Taylor Vince who was in “Trapped” with Kevin Bacon. Thus, Tilda Swinton is separated from Bacon by two degrees.

(To play this game online, go to http://oracleofbacon.org. It’s actually quite hard to get a high number).

Back to our friend, Paul Erdős (http://en.wikipedia.org/wiki/Paul_Erd%C5%91s). He was a famous Hungarian mathematician known for publishing the most papers (~1525) of any mathematician (among other things).

 A photo of Paul Erdős (from Wikipedia)

Breaking down a research article

Everyone does it. It’s almost never formally taught. It’s hard to master, especially at the beginning. Some people struggle with it their whole lives.

Did you guess what I’m talking about?

Reading a research article! (If you were thinking of something else, you’re probably at the wrong blog.)

Reading research articles is an integral part of being a scientist. However, there is rarely a formal instruction for this vital skill.

Fortunately, some educators are working to remedy this problem. A trio of scientists/education researchers developed the CREATE method for reading papers: Consider, Read, Elucidate the hypotheses, Analyze and interpret the data, and Think of the next Experiment. (http://www.teachcreate.org/ )

Lab Reports for Grown-Ups

Grid notebooks, hand-written graphs, switching the carbon paper every time you turned a page. Such are the memories aroused by the mere mention of lab reports.*

To this day, I still remember the strict guidelines of high school lab reports: Hypothesis, Introduction, Materials, Methods, Data/Results, Analysis, and Conclusion.

Scientists write articles instead of lab reports. Articles are reminiscent of lab reports, but the formatting is slightly different, as we explore below.

Five hidden facets of numbers

We live in a world flooded with numbers. News stories, nutrition labels, results from research studies, and even sports highlights are riddled with numbers! Numbers are comforting; they seem solid and dependable.

“The numbers don’t lie.” But what if they do? Numbers can be manipulated to tell contradictory stories. Here are five things to think about next time you see a reported number.

1. Error Margin
2. Sample Size
3. Sample Bias

4. Replication
5. Rounding Errors