SPSS graphing

[Please download a copy of this document and put all your answers in this document.]

[You can study with other students on this assignment, but you must write the answers yourself. If your assignment paper is the same as other student, both of your grades would be low.] When indicating showing software output in a question, please place them right after your answer for each part of the question. In this assignment, statistical software means SPSS.

Part I

Please use the sample data from students to perform the following tasks. All subjects in the sample are in normal health and physical condition.

Link to Data: http://gchang.people.ysu.edu/stat/ClassdataMPH_19x.xls

(The weight data are in pounds and the height data are in inches.)

(Use weight and height data to compute Body Mass Index (BMI). Please find the BMI Formula from Internet and compute the compute BMI using statistical software.)

1. Test whether the average Body Mass Index for the student population where the student sample was drawn is different from 25, at 5% level of significance, using the sample data above. You must state null and alternative hypothesis, check normality assumption, report p-value, test statistic value, and draw a proper conclusion.

Null hypothesis:   Mean = 25, The average BMI is 25.

Alternative hypothesis:  The average BMI is different from 25.

Report p-value from the normality test and conclusion: P-value = 0.436, since p value is bow less than 0.05, so we do not reject null hypothesis.

Report p-value from the t-test and the conclusion:  P-value = 0.95. Since the p-value is not less than 0.05, so we do not reject null hypothesis.  There is no sufficient evidence to support the alterative hypothesis that the average BMI is statistically significantly different from 25.

1. Find the sample size so that the test can have a 95% power to detect a BMI average that is half a standard deviation from the mean, 25, (25 is the mean under the null hypothesis) at 5% level of significance, using a two-sided test.

1. Find the 95% confidence interval for estimating the average BMI for the sampled population.

(23.3487, 26.5517) 24.9802±1.6015

1. Find the sample size that would be required if you wish the estimation of the mean to have a margin of error no more than 0.2. (Use the data to estimate the standard deviation for estimating the sample size.)

N=  = 1.96² * 2.8² / 0.2² = 753