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I have a data set of RNA reaction values of breast cancer. I want to figure out which RNAs are essential genes by Logistic Regression & LASSO.

The data set has no negative samples. What should I do to ensure the method will give a reliable result?

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Assuming that your DV is whether the sample is negative or positive, there is nothing you can do here with this sample alone. You can't distinguish negative from positive if you no negatives. You might be able to compare results to results from some other study, but that is very tricky.

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I think this problem is very common while dealing with chips, could you tell me the general solution? – HikaruSama Dec 8 '12 at 2:44
I can't see that there IS a general solution, at least within logistic regression. With chips, I think survival analysis is often used, but even then, with no failures, I don't see what can be done. – Peter Flom Dec 8 '12 at 14:28

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