Question

Identify the type(s) of bias that may result from each of the following data collection methods. Be sure to explain.

a) A school has 400 grade 9’s, 375 grade 10’s, 300 grade 11’s and 325 grade 12’s. Twenty students from each grade are surveyed.

b) A survey is sent home with student report cards asking parents’ opinions on the format of the report card.

c) To determine if the city bus schedule is working, a sample of people is taken from the bus terminal located at the mall.

The frequency distribution table below summarizes a study that examined the number of times respondents exercised in a month.

Number of Times per Month. Frequency

0-4 1

5-9 3

10-14 5

15-19 11

20-24 9

a) Draw a histogram for the data.

b) Describe the shape of the distribution.

c) Determine the weighted mean for this grouped data.

Answer 1

asper company policies i am answering one question only.

Q2)

a)

b)
the shape of the histogram is negatively skewed.
there are very few observations with less Number of Times per Month

c)

LOWER	UPPER	X	Fi	Xi*Fi
0	4	2	1	2
5	9	7	3	21
10	14	12	5	60
15	19	17	11	187
20	24	22	9	198
	sum		29	468

MEAN = SUM(XI*Fi)/sum(Fi) = 468/29 = 16.1379