Question

( PLEASE SHOW ALL YOUR WORK)

You will need your ticker code (company abbreviation) for stock prices for this question. Use your ticker code to obtain the closing prices for the following two time periods to obtain two data sets:

March 2, 2019 to March 16, 2019

Data set A

February 16, 2019 to February 28, 2019

Data set B

Take the closing prices from data set B and add 0.5 to each one of them. Treat data sets A and B as hypothetical sample level data on the weights of newborns whose parents smoke cigarettes (data set A), and those whose parents do not (data set B).

a) Conduct a hypothesis test to compare the variances between the two data sets.

b) Conduct a hypothesis to compare the means between the two data sets. Selecting the assumption of equal variance or unequal variance for the calculations should be based on the results of the previous test.

c) Calculate a 95% confidence interval for the difference between means

		A	B
		84.09	83.74
		83.22	84.45
		82.35	84.37
		83.39	83.77
		82.65	84.66
		82.09	85.5
		82.49	85.35
		82.19	86.29
		82.32
		82.4
		83.06
	Mean	82.75	84.76625
	SD	0.617770184	0.887612166

Answer 1

the answers are given in the subparts as given in the question.

in part a) the si^2 has the divisor ni-1.

in part a) we get that the variances are equal...as the hypothesis to be tested is not rejected.so we use fisher's t test for testing the difference between means.

c)as the sample sizes of the two variable A and B are less than 30 then we use the t statistic.here i give the complete derivation of c.i using the statistic.our confidence interval is 95%,so alpha=0.05.and taplha/2,n1+n2-2=2.11(using t table)