Question

1. Levine and coauthors in their paper make the following statements: Humans show considerable interindividual variation in susceptibility to weight gain in response to overeating. The physiological basis of this variation was investigated by measuring changes in energy storage and expenditure in 16 nonobese volunteers who were fed 1000 kilocalories per day in excess of weight-maintenance requirements for 8 weeks. Two-thirds of the increases in total daily energy expenditure was due to increased nonexercise activity thermogenesis (NEAT), which is associated with fidgeting, maintenance of posture, and other physical activities of daily life. Changes in NEAT accounted for the 10-fold differences in fat storage that occurred and directly predicted resistance to fat gain with overfeeding (correlation coefficient 0.77, probability < 0.001). These results suggest that as humans overeat, activation of NEAT dissipates excess energy to preserve leanness and that failure to activate NEAT may result in ready fat gain. a. The data for this problem are in the file called levine data.xlsx. Plot the data and comment on the shape of the data. (what are y and x)? b. Calculate the correlation coefficient and test for it equal to zero. Given the variability in the data what are plausible values for the correlation coefficient? c. Calculated the regression coefficient and verify the test on the slope is the same as the test on the correlation coefficient. Interpret the slope. d. Look at the paper and comment on the conclusions related to this data, do you agree?

1. Levine and coauthors in their paper make the following statements: Humans show considerable
interindividual variation in susceptibility to weight gain in response to overeating. The physiological basis of this
variation was investigated by measuring changes in energy storage and expenditure in 16 nonobese volunteers who
were fed 1000 kilocalories per day in excess of weight-maintenance requirements for 8 weeks. Two-thirds of the
increases in total daily energy expenditure was due to increased nonexercise activity thermogenesis (NEAT), which is
associated with fidgeting, maintenance of posture, and other physical activities of daily life. Changes in NEAT
accounted for the 10-fold differences in fat storage that occurred and directly predicted resistance to fat gain with
overfeeding (correlation coefficient 0.77, probability < 0.001). These results suggest that as humans overeat,
activation of NEAT dissipates excess energy to preserve leanness and that failure to activate NEAT may result in ready
fat gain.
a. The data for this problem are in the file called levine data.xlsx. Plot the data and
comment on the shape of the data. (what are y and x)?
b. Calculate the correlation coefficient and test for it equal to zero. Given the variability in
the data what are plausible values for the correlation coefficient?
c. Calculated the regression coefficient and verify the test on the slope is the same as the
test on the correlation coefficient. Interpret the slope.
d. Look at the paper and comment on the conclusions related to this data, do you agree?

Added by Kathryn A.

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