Reference no: EM132337967
Inferences on 2 Means - Independent Samples Assignment -
Q1. The table below summarizes the data on changes in BMI (body mass index) after one year of a program in which the subjects in the Experimental Group received a one year intervention designed to decrease consumption of sugary beverages and the Control Group received no treatment.
Group 1 (Experimental Group)
|
Group 2 (Control Group)
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x-1 = 0.60
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x-2 = 0.63
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s1 = 0.20
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s2 = 0.20
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n1 = 110
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n2 = 114
|
One goal of the study was to determine whether the change in BMI was less for the experimental group than for the control group. (α = 0.05)
(a) Write the alternative hypothesis:
H0: μ1 = μ2
H1:
(b) Use the 2-SampT-Test (Pooled:No) on your graphing calculator. Give the value of the test statistic.
(c) Give the P-value.
(d) State your decision.
(e) State your conclusion about the population mean changes in BMI.
(f) Use the 2-SampTInterval procedure (Pooled: No) on your calculator to construct a 99% confidence interval for the difference of means.
(g) Interpret this interval using the template on the notes page. (Remember the 2nd sentence because there are 2 samples).
Q2. Researchers wanted to determine whether the reaction time (in seconds) of males differed from that of females to a go/no go stimulus. The researchers randomly selected 20 females and 15 males to participate in the study. The go/no go stimulus require the student to respond to a particular stimulus and not to respond to other stimuli. The results are as follows:
Female Students
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Male Students
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0.588
|
0.652
|
0.442
|
0.293
|
0.375
|
0.256
|
0.427
|
0.340
|
0.636
|
0.391
|
0.367
|
0.654
|
0.563
|
0.405
|
0.377
|
0.646
|
0.403
|
0.377
|
0.374
|
0.465
|
0.402
|
0.380
|
0.403
|
0.617
|
0.434
|
0.373
|
0.488
|
0.337
|
0.443
|
0.481
|
0.613
|
0.274
|
0.224
|
0.477
|
0.655
|
Test the hypothesis that there is a difference in mean reaction times between males and females. Use a significance level of α = 0.05. (You are given that normal probability plots and box plots indicate that the data are approximately normal and that there are no outliers.)
(a) State the null and alternative hypotheses.
(b) Use the 2-SampT-Test on your calculator (non-pooled). Give the value of the test statistic.
(c) Give the P-value.
(d) State your decision.
(e) State your conclusion about the population mean reaction times.
(f) Construct a 95% confidence interval for the difference of means. (Use the non-pooled 2-SampTInterval procedure on your calculator.)
(g) Interpret this interval.
Q3. Interpret calculator display: The following TI-84 Plus calculator display presents the results of a hypothesis test for the difference between two means. The sample sizes are n1 = 25 and n2 = 28.
![148_figure.png](https://secure.expertsmind.com/CMSImages/148_figure.png)
a. Is this a left-tailed test, a right-tailed test, or a two-tailed test?
b. How many degrees of freedom did the calculator use?
c. What is the P-value?
d. What is the decision at the α = 0.05 level?
Q4. Interpret calculator display: The following TI-84 Plus calculator display presents a 99% confidence interval for the difference between two means. The sample sizes are n1 = 50 and n2 = 42.
![1936_figure1.png](https://secure.expertsmind.com/CMSImages/1936_figure1.png)
a. Compute the point estimate of μ1 - μ2.
b. How many degrees of freedom did the calculator use?
c. Fill in the blanks: We are 99% confident that the difference between the means is between __________________ and _____________________.