Drilling into the past. Drilling down beneath a lake in Alaska yields chemicalevidence

Chapter 0, Problem 5.35

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Drilling into the past. Drilling down beneath a lake in Alaska yields chemicalevidence of past changes in climate. Biological silicon, left by the skeletons ofsingle-celled creatures called diatoms, is a measure of the abundance of life in thelake. A rather complex variable based on the ratio of certain isotopes relative toocean water gives an indirect measure of moisture, mostly from snow. As we drilldown, we look further into the past. Here are data from 2300 to 12,000 yearsago:14(a) Make a scatterplot of silicon (response) against isotope (explanatory).Ignoring the outlier, describe the direction, form, and strength of the relationship.The researchers say that this and relationships among other variables theymeasured are evidence for cyclic changes in climate that are linked to changes inthe suns activity.(b) The researchers single out one point: The open circle in the plot is anoutlier that was excluded in the correlation analysis. Circle this outlier on yourgraph. What is the correlation with and without this point? The point stronglyinfluences the correlation. Explain why the outlier moves r in the directionrevealed by your calculations.