Drilling down beneath a lake in Alaska yields chemical evidence of past changes in climate. Biological silicon, left by the skeletons of single-celled creatures called diatoms, is a measure of the abundance of life in the lake. A rather complex variable based on the ratio of certain isotopes relative to ocean water gives an indirect measure of moisture, mostly from snow.

As we drill down, we look further into the past. Here is a scatterplot of data from 2300 to 12,000 years ago:

(a) Identify the unusual point in the scatterplot. Explain what’s unusual about this point.

(b) If this point was removed, describe the effect on i. the correlation.
ii. the slope and y intercept of the least-squares line.
iii. the standard deviation of the residuals.

Transcribed Image Text:

Silicon 350- 300- 250- 200 150 100- 50 0. -21.8 -21.4 -21.0 00 -20.6 -20.2 Isotope -19.8 -19.4