Monday, March 30, 2015

Mysteries of Life and Death

Here's another scatterplot, this one from xkcd, with subjective placement of various mysteries into the four quadrants by degrees of weird, not weird, or explanation, no explanation. It's sad, but what is the quadrant for Germanwings Flight 9525?

Monday, March 23, 2015

You Move Me

Here's an example an interactive linear regression demonstration which is like many programs that, these days, are included with nearly all basic statistics textbooks. This one works well and it's easy to move around outliers as well as placing data points close to the mean, in both cases watching what happens to both the slope and the intercept. It makes for many more fun explorations. Via Statistical Modeling, Causal Inference, and Social Science.

Monday, March 16, 2015

Let it stop, let it stop, let it stop

Here in Washington, DC we certainly have not see the anywhere near the snow totals that Boston has seen this winter. But I am certainly tired of shoveling! Has the Snow Finally Stopped? is a question that Harry Enten at Five Thirty Eight's Data Lab has examined using data on the date of the last measurable snow over the last 50 years in various US cities with data from the National Oceanic and Atmospheric Administration (NOAA).. In the graphic above he plots the lower and upper quartiles of the date of the last snow along with the median. For Washington, DC here is a stemplot of the frequency distribution of those dates.

December  0 | 9   
          1 |   
          1 |   
          2 |   
          2 |   
          3 |   
January   0 |   
          0 |   
          1 |   
          1 | 5   
          2 |   
          2 | 57   
          3 | 1   
February  0 |   
          0 | 7   
          1 | 12234   
          1 | 5789   
          2 | 0334   
          2 | 577   
March     0 | 12   
          0 | 567888899   
          1 | 023344   
          1 | 8   
          2 | 011   
          2 | 5567   
          3 |   
          0 |   
          0 | 777

It's interesting that the overall latest measurable snow in Washington, DC has only occurred on April 7 (in the three years: 1972, 1990, and 2007). Reminds me of another early April pattern that held up for years. 

Over 3/4 of these snow dates are behind us now. But, there are still 11  years out of the past 50 that saw measurable snowfall after today's date of March 16. Based on these data, we can estimate the chance of more snow to be 22%. Let's bet against it!

Monday, March 9, 2015

Daily Double - Maybe

Coming across the Daily Doubles in the TV game show Jeopardy! can quickly propel contestants into the lead.  They do not have to compete with others to come up with the question and they can wager a large sum. In 2014 contestant Arthur Chu upset Jeopardy! traditionalists by bouncing around the board hoping to hit upon a Daily Double. Using data from the fan site J!Archive, Nathan Yau from Flowing Data has tabulated the locations of the Daily Doubles for 31 seasons totaling 13,633 Daily Doubles and shown them as relative frequencies. The darker the color the more likely a Daily Double for that position. Clearly, the fourth row is most favored by a small amount.

Monday, March 2, 2015

Gas Pump Dings

Here's another gas pump distribution. Inattentive users of the pump's nozzle have carelessly returned it to its home. In the process they have dinged the vertical panel on the left. The nozzle has its set home, but the users have sometimes started too high for its return resulting in a few dings on the upper regions of the panel. Similarly, there are a few dings on the low end of the panel. The majority of the dings are in-line with the nozzle's home. It's a distribution pattern we've seen often: few marks high, few marks low, and most marks in between.