“Correspondence analysis provides tools for analyzing the associations between rows and columns of contingency tables. A contingency table is a two-entry frequency table where the joint frequencies of two qualitative variables are reported. For instance a (2 x 2) table could be formed by observing from a sample of n individuals two qualitative variables: the individual’s sex and whether the individual smokes. The table reports the observed joint frequencies. In general (n x p) tables may be considered.

“The main idea of correspondence analysis is to develop simple indices that will show the relations between the row and the column categories. These indices will tell us simultaneously which column categories have more weight in a row category and vice-versa. Correspondence analysis is also related to the issue of reducing the dimension of the table…” (p. 341)

Applied Multivariate Statistical Analysis

“A frequently applied paradigm in analyzing data from multivariate observations is to model the relevant information (represented in a multivariate variable X) as coming from a limited number of latent factors. In a survey on household consumption, for example, the consumption levels, X, of p different goods during one month could be observed. The variations and covariations of the p components of X throughut the survey might in fact be explained by two or three main social behavioral factors of the household…These unobserved factors are much more interesting to the social scientist than the observed quantitative measures (X) themselves, because they give a better understanding of the behavior of households.

“How can we provide a statistical model addressing these issues and how can we interpret the obtained model? This is the aim of factor analysis.” (p. 276)

Applied Multivariate Statistical Analysis

“…Two partners in a human chromosome pair…often line up next to one another in parallel array, look each other over, compare their respective DNA sequences, and then swap genetic information. One frequent result is that a gene sequence present on one chromosome will now replace the corresponding sequence carried by its partner. Before this information transfer, two distinct versions of a gene may have resided on the two paired chromosomes; afterward, one of these versions is lost, being replaced by a duplicated version of the gene originally present on the other chromosome. The result is two identical copies of a gene in a cell that previously carried two dissimilar versions.” (p. 75)

“Estrogen is a fully natural hormone, native to the body, yet it contributes to carcinogenesis in the breast and ovaries. In the breast, it drives the proliferation of cells lining the milk ducts during the menstrual cycle and pregnancy. The monthly multiplication of these mammary epithelial cells is followed by their die-off, this cycle repeating itself over and over in most women from menarche to menopause–generally between ages twelve and fifty.

“Many researchers trace the roots of breast cancer to these repeated bouts of estrogen-driven proliferation. The increased incidence of this disease in modern times seems connected to dramatically increased menstrual cycling. Due to greatly improved nutrition, menarche begins four or five years earlier in late-twentieth-century girls than it did in their great-grandmothers. In addition, reproductive practices have changed in Western society. Childbearing and breast feeding, both of which suppress menstrual cycling, are now postponed and, when they occur, encompass only a few years of adult life, unlike a century ago, when three decades of a woman’s life were often involved in cycles of birth and lactation.” (p. 60-61)