What is l1-regularized logistic regression? What is the purpose of l1-regularization?

What is the precise interpretation of a number in the structure matrix of the discriminant analysis output? 

A researcher conducting a principal component analysis has obtained a KMO index of 0.65 and found that the significance level for Bartlett’s test of sphericity is 0.02. What is the null hypothesis associated with Bartlett’s test of sphericity? What, should the researcher conclude from the KMO index and significance level? Be as specific as possible in your answers.

Consider five objects measured on three variables (x1, x2, and x3) as shown below.  The current clusters are: Cluster 1 contains objects 1 and 5, and Cluster 2 contains objects 2, 3, and 4.  Perform an iteration of K-means by computing the current centroids (cluster centers) and the squared Euclidean distances from each object to the centroids and reassigning each object to its nearest cluster center. Show all of your work for computing the centroids and the distances. Object 1 2 3 4 5 x1 measure 12 3 10 2 2 x2 measure 3 9 2 10 7 x3 measure 3 5 6 1 9  

A sample of n = 5 objects are measured on two variables, x and y.  Their measurements are shown in the table below.  Compute the product-moment correlation coefficient between x and y. Be sure to show all necessary work. Object 1 2 3 4 5 x-measure 5 12 6 2 10 y-measure 9 6 7 14 4  

What is the precise interpretation of the bivariate (or Pearson) correlation measure between two variables x and y? How does a measure of partial correlation between the same two variables differ from this measure?

I found this discussion on answerbag.com. It’s amazing what one can find on the Internet! 🙂 —————————————————————————– Q: Why are gram–positive bacteria typically more resistant than gram–negative bacteria to antibiotics that disrupt plasma membranes, such as polymyxin B? A. Gram positive bacteria have a cell wall surrounding the organism, including the plasma membrane. A plasma membrane is usually made up of lipids, which can easily move around to let other molecules in. Meanwhile, a cell wall is a more rigid structure that is not as easily broken. The best way I understand it is by imagining someone wearing a suit of armor. The armor is like the cell wall, which protects the person (or bacteria) from arrows (or the antibiotics). The person with armor is better protected than another person without any armor. Likewise, a bacterium with a cell wall has more protection than one with only a plasma membrane. ——————————– Polymyxin B is a cationic surface agent that binds to LPS in the cell, which results in increased permeability and cell death. Gram-positive bacteria are more resistant to polymyxin B than Gram-negative bacteria for all of the following reasons EXCEPT:

Explain why you eliminated the other 3 pathogens in the previous question about gamma irradiation. (Why isn’t gamma irradiation used to kill these pathogens in food products?)  Be specific and complete in your response. The choices were:  viruses protists bacteria molds prions

Why can’t an aerobic bacterium produce as much energy as an animal cell can produce from a gram of sugar?

How does ATP release energy that can be used by living cells?