Introductory Biostatistics
For the cases, proportion of exposure¼ 84 397 ¼ 0 :212 or 21:2% The results reveal di¤erent exposure histories: The proportion ...
ing alters the e¤ect of employment in shipyards as a risk for lung cancer. In that case,smokingis not only a confounder, it is a ...
in a large population can be classified as truly positive or negative for a partic- ular disease; this true diagnosis may be bas ...
possible cancer) and 23,724 women whose cervices are acceptably healthy. A test was applied and results are tabulated in Table 1 ...
1.1.3 Displaying Proportions Perhaps the most e¤ective and most convenient way of presenting data, espe- cially discrete data, i ...
wedges that correspond to the magnitude of the proportions for various cate- gories. A pie chart shows the di¤erences between th ...
Line Graphs A line graph is similar to a bar chart, but the horizontal axis represents time. In the applications most suitable t ...
Example 1.10 The line graph shown in Figure 1.6 displays the trend in rates of malaria reported in the United States between 194 ...
change rateð%Þ¼ new valueold value old value 100 In general, change rates could exceed 100%.They are not proportions(a pro- p ...
For the new AIDS cases transmitted from mothers to newborns, we have 17%¼ 547 ð1988 casesÞ 1988 cases 100 leading to 1988 c ...
such as age, gender, and race.Specific ratesconsider these di¤erences among subgroups or categories of diseases.Adjustedorstanda ...
potential source of bias; e¤ort should be expended on reducing the num- ber of subjects in this category) The contribution of ea ...
1.2.3 Standardization of Rates Crude rates, as measures of morbidity or mortality, can be used for population description and ma ...
for each age group of each of the two populations being compared. For example, for age group 0–4, the U.S. population for 1970 w ...
of this, an adjusted rate is artificial; it does not reflect data from an actual population. The numerical values of the adjuste ...
ratio¼ a b whereaandbaresimilar quantitiesmeasured fromdi¤erent groupsor under di¤erent circumstances. An example is the male/fe ...
Suppose that each subject in a large study, at a particular time, is classified as positive or negative according to some risk f ...
2.A=CandB=Dare the odds in favor of having been exposed to the factors from groups with or without the disease. These two odds c ...
[The subscriptein RReindicates that we are calculating the relative risk (RR) forex-smokers.] (b) For current smokers, RRcF 38 = ...
The interpretation above of the concept of an odds ratio as an odds can be generalized as follows. The aim here is to present an ...
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