Question

An adolescent development researcher conducts a study investigating the affect of screen time (TV, video games, social media, etc...) on sleep habits. Each participant tracks their daily screen time and nighttime sleep for one month, and reports the average daily screen time and the average amount of nighttime sleep. The results are in the table below. Copy and paste the link to create a copy in Google Sheets.

https://tinyurl.com/ybtc9q45

Average Daily Screen Time (hours)	Average Nighttime Sleep (hours)
7.4	4.9
8.7	6
0	6.7
9.8	3.1
6.6	5.3
8.3	6.6
3	6.7
1.1	7.7
6.4	7.1
1.1	9.4
2.7	6.8
2	9.1
6	5.9
2	7.2

a. Calculate the correlation coefficient using the Google Sheets function =CORREL. Round your answer to 2 decimal places.

b. Choose the equation for the line of best fit in the form y = mx + b.

Select your answer from one of the following options.

• a. ?=−1.51?+8.30
• b. ?=−0.36?+14.63
• c. ?=−1.51?+14.63
• d. ?=−0.36?+8.30

c. We see in the table that one participant engaged in no screen time, and got an average of 6.7 hours of sleep per night. If this data point were deleted, what would happen to the correlation coefficient?

Select your answer from one of the following options.

• a.The correlation would be stronger, because this data point is close to what the model predicts.
• b.The correlation would be weaker, because this data point is much lower than the model predicts.
• c.The correlation would be weaker, because this data point is close to what the model predicts.
• d.The correlation would be stronger, because this data point is much lower than the model predicts.

Answer 1

a.

b.

Select the two columns.
Click Insert > Chart > Select Chart > Go to Customize tab in Chart Editor > Series > select the checkbox for Trendline > from Label dropdown menu, choose "Use Equation"

d. y = -0.36x + 8.3

c.

d.The correlation would be stronger, because this data point is much lower than the model predicts.