Download data file: https://drive.google.com/open?id=0B6i_JzkQ2f6IYWxZSTdyRjRLWE

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https://drive.google.com/open?id=0B6i_JzkQ2f6IYWxZSTdyRjRLWE0

The systolic and diastolic blood pressure (mm Hg) was recorded for 30 patients with moderate essential hypertension (Table below) [1]. Half of the group was measured immediately after taking the drug captopril (Drug=2) while the other half received a placebo (Drugs 1). The dataset b1d.dat is Using R software: (d) Does there appear to be a difference in the BPs recorded for patients who received captopril compared to those who received a placebo? (e) Plot the data (using a different symbol for each Drug) and the fitted regression lines, and comment on any differences between the patients within each Drug group.

Explanation / Answer

d).

1.

Ho:µA = µB:There is no significance difference of systolic blood pressure by using Drug 1 or Drug 2

Ha:µA µB:There is a significance difference of blood pressure by using Drug 1 or Drug 2

Here in alternative hypothesis the claim is mean numbers are not equal. So have to use not
equal sign for alternative hypothesis.Since not equal has used in alternative hypothesis this is a Two Tail Test
Here we only know the sample standard deviation, so have to use the t test.

Two-Sample T-Test and CI: Diastolic, Drug_1_1

Two-sample T for Diastolic

Drug_1_1   N   Mean StDev SE Mean
1         15 102.7   13.0      3.4
2         15 112.3   10.5      2.7

Difference = mu (1) - mu (2)
Estimate for difference: -9.60
95% CI for difference: (-18.45, -0.75)
T-Test of difference = 0 (vs not =): T-Value = -2.23 P-Value = 0.035 DF = 26

Since P value is less than 0.05 lie in the rejection region (P value is 0.035), we cannot accept null hypothesis in favor of alternative hypothesis at 5% significance level.In practical we can conclude that there is a significance difference of systolic blood pressure is occurs by using Drug 1 or Drug 2 in 95% confidence level.

2.

Ho:µA = µB:There is no significance difference of diastolic blood pressure by using Drug 1 and Drug 2

Ha:µA µB:There is a significance difference of blood pressure by using Drug 1 and Drug 2

Here in alternative hypothesis the claim is mean numbers are not equal. So have to use not
equal sign for alternative hypothesis.Since not equal has used in alternative hypothesis this is a Two Tail Test
Here we only know the sample standard deviation, so have to use the t test.

Two-Sample T-Test and CI: Systolic, Drug_1

Two-sample T for Systolic

Drug_1   N   Mean StDev SE Mean
1       15 133.5   26.1      6.7
2       15 176.9   20.6      5.3

Difference = mu (1) - mu (2)
Estimate for difference: -43.47
95% CI for difference: (-61.10, -25.84)
T-Test of difference = 0 (vs not =): T-Value = -5.07 P-Value = 0.000 DF = 26

Since P value is less than 0.05 lie in the rejection region (P value is 0.000), we cannot accept null hypothesis in favor of alternative hypothesis at 5% significance level.In practical we can conclude that there is a significance difference occurs in diastolic blood pressure by using Drug 1 or Drug 2 in 95% confidence level.

(e)

Since the Dependant variable- Blood Pressure is Quantitative (Ratio) and Independent Variable (Nominal) Categorical we cannot use Regression Lines to Represent the data and to check about the individual values we can use box plots.

According to Box Plots there is no unusual individual observations or residuals.

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