GCRC Hypothesis Testing

HYPOTHESIS TESTING

? The logic of hypothesis testing ? One-sample vs. two-sample problem ? Null vs. alternative hypothesis ? Type I and type II error ? Significance level ? Power 1- ? One-sided vs. two-sided test ? Test statistic ? P-value ? Statistical tests and diagnostic tests ? Power and sample size

Decisions under uncertainty: A choice between two conflicting theories

? A court psychiatrist is called upon to pronounce an accused murderer "sane" or "insane"

? The FDA "approves" or "rejects" an application by a pharmaceutical house to get a flu vaccine licensed

? A stockbroker "buys" or "sells" a certain stock

To make controlled decisions we need:

? A formal decision rule (a test) ? Characterize the performance of the decision procedure ? Compare decision rules

Using statistical testing => Evidence based decisions

A DIAGNOSTIC TEST FOR RESIDUAL DISEASE IN BREAST CANCER PATIENTS

A treated breast cancer patient

Question: Is there any residual disease in the patient? The answer is important for further treatment or screening for relapse

Null hypothesis and the alternative one H0 = No residual disease H1 = Residual disease present

Bills, A.C., Green, W.F., Tsodikov, A., Carey, M., Perkins, S., Petersen, F.B., Kelley, L. (1999) Cytokeratin positive cells in peripheral blood stem cell collections from normal donors and patients with non-epithelial cell-derived tumors, Cytotherapy, Vol.1, 389-399.

Quantify the effect: Measure residual disease

Marker of a cancer cell: Cytokeratin

A breast cancer cell is more likely to be Cytokeratine-positive than a normal cell. Nothing is perfect.

Measure of residual disease T (test statistic) Proportion of cytokeratin-positive cells in peripheral blood stem cell collection

Rcmdr

Put variable names on top of the file Data/Import data/From textfile Give a name: Dataset View dataset to check what happened Data/Active dataset/Subset active dataset/ Expression: (BC==1) Name: BC1; Data/Active dataset/Select active dataset

or press name -> Dataset Data/Active dataset/Subset active dataset/ Expression: (BC==0) Name: BC0 Graphs/Histograms -> IHC with BC0 and BC1

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