-Anyone wanna help a sister out??-
2 answers:
Answer:
Option A - The researcher made an error because −1 ≤ r ≤ 1.
Step-by-step explanation:
Given : A researcher is trying to find out if there is a correlation between the U.S. economy and the number of hours spent on social media. The researcher determines that the correlation coefficient is r = 1.26.
To find : What does this value mean?
Solution :
By definition of correlation coefficient,
The correlation coefficient r measures the strength and direction of a linear relationship between two variables on a scatter plot.
The value of r is always between +1 and –1 i.e,
According to researcher,
The correlation coefficient is r = 1.26 >1
So, From the options it means
The researcher made an error because −1 ≤ r ≤ 1.
Therefore, Option A is correct.
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Answer:
c. Smoking is associated with lower birth weights. When smokers are compared to nonsmokers, we are 95% confident that the mean weight of babies born to nonsmokers will be between 76.5 grams to 486.9 grams more than the mean birth weight of babies born to smokers.
Step-by-step explanation:
The difference in mean birth weights (nonsmokers minus smokers) is 281.7 grams with a margin of error of 205.2 grams with 95% confidence.
Then, we know that the 95% confidence interval is (76.5, 486.9)
<em>a. We are 95% confident that smoking causes lower birth weights by an average of between 76.5 grams to 486.9 grams.</em>
False, it interprets the confidence interval as a probability for individual cases. The confidence interval is a range for the population mean.
<em>b. There is a 95% chance that if a woman smokes during pregnancy her baby will weigh between 76.5 grams to 486.9 grams less than if she did not smoke.</em>
False, it interprets the confidence interval as a probability for individual cases. The confidence interval is a range for the population mean.
<em>c. Smoking is associated with lower birth weights. When smokers are compared to nonsmokers, we are 95% confident that the mean weight of babies born to nonsmokers will be between 76.5 grams to 486.9 grams more than the mean birth weight of babies born to smokers.</em>
True.
<em>d. With such a large margin of error, this study does not suggest that there is a difference in mean birth weights when we compare smokers to nonsmokers.</em>
There is enough evidence, as the lower bound of the confidence is positive. This means that there is only a probability of 0.05/2=0.025 that the true mean weight difference is smaller than 76.5 grams.