1.The following age pyramid was shown and described in class. Compare the age di
ID: 3296341 • Letter: 1
Question
1.The following age pyramid was shown and described in class. Compare the age distribution for the US from 1990 (inner dark red area) to that predicted in 2050 (outer light pink area). In particular, describe the difference in the group aged 85 and older in terms of percentage of the total population. Also, give two reasons why that age group has changed in the percentage of all people.
2. It is now accepted that tobacco smoking is a risk factor for several diseases, including but not limited to lung cancer, COPD, heart disease and other cancers not related to the lungs. In order to determine the risk of all of these diseases due to smoking, what would be the best study design? Why?
3. A study was performed to evaluate whether zidovudine (AZT) administered to HIV-infected pregnant women and their newborns could reduce the rate of transmission from mother to infant. The final study population consisted of 363 live births. The mothers of 180 were randomly assigned to the AZT arm of the study and 13 of the infants developed HIV infections. The mothers of 183 were randomly assigned to receive a placebo and 40 of those infants developed HIV.
a) What type of study is this?
U.S. age pyramid 2050 2000 1950 1900 Age 85+ 80-84 75-79 70-74 65-69 60-64 55-59 50-54 45-49 40-44 35-39 30-34 25-29 20-24 15-19 10-14 5-9 0-4 15 million 12 6 Males 9 12 5 Females Source: http://www.ctmt.com/pdfs%5CemergingDirections%5Cdemographicsasdestiny.pdfExplanation / Answer
3. If we formulate the given problem into a contingency table, the table looks as follows :
We have to test whether application of AZT has any effect on not developing HIV infections among the infants.
This is a two way contingency table and we need to test whether the two factors are dependent or not.
So chi-square test of Independence between the two factors (HIV infections in infants and application of AZT) will be appropriate.
HIV infected infants HIV not infected infants TOTAL AZT 13 167 180 PLACEBO 40 143 183 53 310 363Related Questions
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