STAT 100 - C40 Elementary Statistics for Applications
Assignment - 2
Due on 20 May, 2020 by 1 pm
Total Marks: 25
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MARKS
1. The following data represent the social ambivalence scores for 14 people as measured by a[9]
psychological test. (The higher the score, the stronger the ambivalence.)
XXXXXXXXXX XXXXXXXXXX
Find the interquartile range, five number summary and sketch a box and whisker plot for the
data. Find if there are any outlier(s)?
2. A social skills training program was implemented with seven mildly challenged students in[10]
a study to determine whether the program caused improvement in pre/post measures and
ehavior ratings. For one such test, the pre - and posttest scores for the seven students are
given in the table.
Subject Pretest, x Posttest, y
Earl XXXXXXXXXX
Ned 90 88
Jasper XXXXXXXXXX
Charlie 106 98
Tom 91 104
Susie 91 94
Lori 89 98
a) Calculate the linear co
elation coefficient, r. Describe the relationship.
) Calculate the line-of-best-fit(linear regression line).
c) Estimate the post test score if the pretest score was 98.
3. The linear co
elation coefficient of a set of data points is -0.85.[2]
a) Is the slope of the regression line positive or negative?
) Determine the coefficient of determination.
4. A regression analysis between sales (y in $1000) and advertising (x in $100) resulted in the[2]
following least-squares line: ŷ = 82 + 7x. Given this information, if advertising costs were
$900, what could we reasonably expect the amount of sales (in dollars) to be?
5. A regression analysis between weight (y in kg) and height (x in cm) resulted in the following[2]
least-squares line: ŷ = –20 + 0.5x. Taking this into consideration, if the height is increased
y 1 cm, what does this imply about the change in the weight, on average?
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