Tag Archives: chi-square

Dicking around with Data

I have my first ounce of legitimate free time today and what do I do with it?


Today’s feature: analyzing Nobel laureates by birth dates.

Nobel Prizes are awarded for achievement in six different categories: physics, chemistry, physiology/medicine, literature, peace, and economic sciences. Thus far, there have been 863 prizes awarded to individuals and organizations.

The Nobel website has a bunch of facts on their laureates, including a database where you can search by birthday. So because I’m me and I like to analyze the most pointless stuff possible, here’s what today’s little flirtation with association entails:

1. Does the birth month of the laureate relate in any way to the category of the award (chem, medicine, etc.)?

2. Does the zodiac sign of the laureate in any way to the category of the award?

Vroom, vroom! Let’s do it.

Pre-Analysis: Examining the data

So I should preface this. I decided, upon inspecting the observed contingency table comparing Birth Month and Award Category, to drop the Economics prize altogether. I calculated that the expected cell counts would be very small (because the Economics category is actually the newest Nobel category); such small cell counts would totally throw the chi-square test. So we’re stuck with the other five categories for our analysis.

Question 1: Relation of birth month to award category

Treating Birth Month as a categorical variable (with categories January – December) and Award Category as another categorical variable (with categories equal to the six award categories), I performed a chi-square test to examine if there is an association between the two categories.

Results: χ2 (45)= 81.334, p = 0.0007345. This suggests, using a critical value of .05, that there is a significant relationship between birth month and award category.

Examining the contingency table again (which I’d post here but it’s being a bitch and won’t format correctly, so I’m just going to list what I see):

  • Those born in the summer months (June – August) and the months of late fall (October, November) tend to own the Peace and Literature prizes.
  • August-, September-, and October-born have most of the Physics prizes.
  • The Chemistry prizes seem pretty evenly distributed throughout the months.
  • The summer-born seem to have the most awards overall.

Question 2: Relation of zodiac sign to award category.

I suspected this to have a similar p-value, just solely based on the above analysis.

Results: I get a χ2 (54) = 199.8912, p < 0.0001. So this suggests, using our same cutoff value, that there is a significant relationship between zodiac sign and award category. Which makes sense, considering what we just saw with the months. But what’s interesting is that just by looking at the size of the chi-square this relationship is actually stronger than the above one.

Looking at the contingency table for this relationship, here are a few of my observations:

  • Aries, Gemini, Virgos, and Libras own the Medicine awards.
  • Cancers, Sagittarians, and Aquarians own the Physics awards.
  • The first five zodiac signs (Aries – Leo) seem to dominate Literature.
  • Capricorns are interesting. They have the least amount of awards overall, but 30% of the awards they do have are in Peace. That’s far more (percentage-wise) than any other sign. Strange noise.