Problem:
Global warming? Because of the high stakes, the falling of the tripod has been carefully observed for many years. If the date the tripod falls has been getting earlier, that may be evidence for the effects of global warming.
Required:
(i) Make a time plot of the date the tripod falls against year.
(ii) There is a great deal of year-to-year variation. Fitting a regression line to the data may help us see the trend. Fit the least-squares line and add it to your time plot. What do you conclude?
(iii) There is much variation about the line. Give a numerical description of how much of the year-to-year variation in ice breakup time is accounted for by the time trend represented by the regression line. (This simple example is typical of more complex evidence for the effects of global warming: large year-to-year variation requires many years of data to see a trend.)