Introductory Biostatistics
significancea; the values 0.01 and 0.05 are common choices fora. Since a test of levelalphais also of levela^0 >a, it is conv ...
group, which is 74.5 mmHg. What are the null hypothesis and alterna- tive hypothesis for this test? 5.3 E. canisinfection is a t ...
ments). Suppose that we know from using an in-person diet interview method in an earlier large study that the standard deviation ...
sedentary persons in this age group is planned to test whether they have higher levels of plasma glucose than the general popula ...
6 Comparison of Population Proportions In this chapter we present basic inferential methods for categorical data, espe- cially t ...
sample is often large enough so as to produce negligible sampling error inp 0 ). Or we could be concerned with a research questi ...
Example 6.1 A group of investigators wish to explore the relationship be- tween the use of hair dyes and the development of brea ...
and controls are sampled either as disease-free persons from the population at risk or as hospitalized patients having a diagnos ...
X^2 ¼ ðbcÞ^2 bþc and the test is known asMcNemar’s chi-square. If the test is one-sided,zis used and the null hypothesis is rej ...
Example 6.3 A study in Maryland identified 4032 white persons, enumerated in a uno‰cial 1963 census, who became widowed between ...
Choose a significance levela, a common choice being 0.05. Calculate thezscore z¼ p 2 p 1 ffiffiffiffiffiffiffiffiffiffiffiffi ...
Example 6.4 A study was conducted to see whether an important public health intervention would significantly reduce the smoking ...
suggesting that they are not the same and that a child seems more prone to taking drug B than drug A. However, the chi-square st ...
It can be seen that the rate of employment for the cases (18.0%) was higher than that for the controls (14.7%), but the di¤erenc ...
It can be seen that the proportion of smokers among the cases (71.7%) was higher than that for the controls (37.7%) and the di¤e ...
Under the null hypothesis and fixed marginal totals, cellð 1 ; 1 Þfrequencyais distributed with mean and variance: E 0 ðaÞ¼ r 1 ...
a¼ 11 r 1 c 1 n ¼ ð 46 Þð 61 Þ 299 ¼ 9 : 38 r 1 r 2 c 1 c 2 n^2 ðn 1 Þ ¼ ð 46 Þð 253 Þð 61 Þð 238 Þ ð 299 Þ^2 ð 298 Þ ¼ 6 : 34 ...
and for heavy smokers, a¼ 14 r 1 c 1 n ¼ ð 17 Þð 110 Þ 163 ¼ 11 : 47 r 1 r 2 c 1 c 2 n^2 ðn 1 Þ ¼ ð 17 Þð 146 Þð 110 Þð 53 Þ ð ...
12150 122203 21170 21242 221217 222220 31114 3123 32196 32250; PROC FREQ; WEIGHT COUNT; TABLES SMOKESHIPCANCER/CMH; The result i ...
z¼ ð 4 2 : 52 Þþð 25 18 : 70 Þ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi 2 : 25 þ 14 : ...
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