Question

The presence of student-owned information and communication technologies (smartphones, laptops, tablets, etc.) in today's college classroom creates learning problems when students distract themselves during lectures by texting and using social media. Research on multitasking presents clear evidence that human information processing is insufficient for attending to multiple stimuli and for performing simultaneous tasks.

To collect data on how multitasking with these technologies interferes with the learning process, a carefully-designed study was conducted at a mostly residential large public university in the Northeast United States. Junco, R. In-class multitasking and academic performance. Computers in Human Behavior (2012)

At the beginning of a semester a group of students who were US residents admitted through the regular admissions process and who were taking the same courses were selected based on their high use of social media and the similarities of their college GPA's. The selected students were randomly assigned to one of 2 groups:

group 1 students were told to text and use Facebook during classes in their usual high-frequency manner;

group 2 students were told to refrain from any use of texting and Facebook during classes.

At the conclusion of the semester the semester GPA's of the students were collected. The results are shown in the table below.

IN-CLASS MUTLITASKING STUDY

Frequent Facebook Use and Texting	No Facebook Use or Texting
x1 = 2.87	x2 = 3.16
s1 = 0.67	s2 = 0.53
n1 = 65	n2 = 65

Question 1. Do texting and Facebook use during class have a negative affect on GPA? To answer this question calculate a 95% confidence interval for ?1??2 where ?₁ is the mean semester GPA of all students who text and use Facebook frequently during class and ?₂ is the mean semester GPA of all students who do not text or use Facebook during class (do NOT use the approximation formula minimum(n₁-1, n₂-1) for the degrees of freedom).

lower limit of confidence interval (use 2 decimal places)
upper limit of confidence interval (use 2 decimal places).

Question 2. Choose the correct interpretation of the confidence interval in question 1. (2 submissions allowed)

Since the confidence interval is entirely negative it appears that students who text and use Facebook during class have a higher GPA than students who do not text and use Facebook during class.Since the confidence interval is entirely negative it appears that students who do not text and use Facebook during class have a lower GPA than students who text and use Facebook during class.    Since the confidence interval is entirely negative it appears that students who text and use Facebook during class have a lower GPA than students who do not text and use Facebook during class.

Answer 1

df = (s1^2/n1 + s2^2/n2)^2/((s1^2/n1)^2/(n1 - 1) + (s2^2/n2)^2/(n2 - 1))

   = ((0.67)^2/65 + (0.53)^2/65)^2/(((0.67)^2/65)^2/64 + ((0.53)^2/65)^2/64)

   = 122

At 95% confidence interval the critical value is t^* = 1.980

The 95% confidence interval for difference in population means is

+/- t^* * sqrt(s1^2/n1 + s2^2/n2)

= (2.87 - 3.16) +/- 1.98 * sqrt((0.67)^2/65 + (0.53)^2/65)

= -0.29 +/- 0.21

= -0.5, -0.08

Lower limit = -0.5

Upper limit = -0.08

2) Since the confidence interval is entirely negative it appears that students who text and use Facebook during class have a higher GPA than students who do not text and use Facebook during class.