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3 weeks ago
Crawling Researchers at the University of Denver Infant Study Center investigated whether babies take longer to learn to crawl in cold months (when they are often bundled in clothes that restrict their movement) than in warmer months. The study sought an association between babies' first crawling age (in weeks) and the average temperature during the month they first try to crawl (about 6 months after birth). Between 1988 and 1991 parents reported the birth month and age at which their child was first able to creep or crawl a distance of four feet in one minute. Data were collected on 208 boys and 206 girls. The graph below plots average crawling ages (in weeks) against the mean temperatures when the babies were 6 months old. The researchers found a correlation of r = -0.70 and the their line of best fit was

= 36 − 0.08AvTemp.



a. Draw the line of best fit on the graph. (Show your method clearly.)
b. Describe the association in context.
c. Explain (in context) what the slope of the line means.
d. Explain (in context) what the y-intercept of the line means.
e. Explain (in context) what R2 means.
f. In this context, what does a negative residual indicate?
Textbook 

Stats: Modeling the World


Edition: 4th
Authors:
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wrote...
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3 weeks ago
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a. Plot 2 points; for example (30, 33.6) and (70, 30.4)
b. The association is linear, moderately strong, and negative, with one outlier. Children seem to crawl earlier when the temperature is higher, though there was an unusually early age observed for a temperature just above 50°.
c. The model suggests that, on average, babies crawl 0.8 weeks earlier for every 10° higher the temperature is.
d. The model predicts that at a temperature of 0° babies would crawl at an average of 36 weeks old (though this may not mean much as no data were collected at such cold temperatures.)
e. 49% of the variability in crawling age can be explained by variations in temperature.
f. A negative residual would indicate that babies crawled at a younger age than the model predicted.
This verified answer contains over 120 words.
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wrote...
3 weeks ago
Thank you for answering so quickly
wrote...
3 weeks ago
Was feeling bored, my pleasure Grinning Face with Smiling Eyes
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