Project #8227 - Statistic

1.    Inastudyof Hodgkin’s disease, T4cell countswere taken on 20 patients in remission.

The data aregiven in thefile “tcell.txt” on RamCT. Copythe data into SASand createa SAS data set.  Add anew variable that is thelogarithms (base e)ofthetcell counts.

tcell.txt

221

342

354

375

456

472

486

507

511

722

843

889

999

1003

1068

1339

1485

1831

2473

3201

 

Use code likethefollowing:

datatcellinfo;

inputtcell;

lgtcell=log(tcell);*createslogbaseecolumn;

datalines;

(put data here)

;

procprint;run;

(a)Use SAS Proc Univariate to get summarystatistics for the T4 cell and logtcell data.

Use code likethefollowing:

procunivariatenormalalpha=0.05;vartcelllgtcell;

histogramtcelllgtcell;

QQplottcelllgtcell;

run;

(b)Use thenormal tests, histograms, and qqplots in theoutput to evaluate thenormalityofthe tcell data and thelog tcell data.  What doyouconclude abouteach?

(c)Compute an estimateofthe mean numberofT4 cells usingtheminimum varianceunbiased estimator presented in class. (Use theclosest entrywhen usingthe table; noneed to interpolate.)

(d)Find the90% two-sided confidence interval forthe mean numberof T4cells.Assumingnormalityofthelogdata computea90% (two-sided)confidence interval forthe mean ofthelogdata.Back transform, i.e.exponentiate, basee, theendpoints oftheinterval, and compare theresults to the interval computed usingthe website.  Which ofthese two confidence intervals is likelyto bebetter?

 

2.    Refer to thedata fromproblem 6.13 which deals with end-of-year bonuses.(a)Perform theindependent two-sample t-test usingthenull hypothesis thatend-of-year

bonusesarethesameformaleandfemaleemployees.  Testattheα=0.05level.  First,give therejection region.  Then, perform the analysis in SAS and report the p-value.Assume equal variances.

 

(b)Explain whythe independent two-sample t-testis appropriate forthis data, rather thanthe paired-sample t-test.

book: an introduction to statistical methods and data analysis 6th edition

Subject Mathematics
Due By (Pacific Time) 06/24/2013 11:00 am
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