1. The table shows the concentration of chlorhexidine (mg) in 15 1-mL
samples that have been removed from a stock solution (5 L) and assayed by
ultraviolet spectroscopy. Calculate the 95% confidence interval of the
population mean.
2.
A clinical trial (n = 35
patients) has been performed in which the volume of distribution of a new
anti-diabetes drug has been calculated as 10.2 ± 1.9 L. Calculate the 95% and 99% confidence limits
of the mean value (assuming that the data originated from a normal
distribution).
3.
Consider the distribution of
hemoglobin levels for the population of children under 6 who have been exposed
to high levels of lead. Suppose that this distribution has σ = 0.85g/100ml.
Because children who have lead poisoning tend to have much lower levels of
hemoglobin than children who do not, we are interested in an upper confidence
limit for µ (the mean of the hemoglobin levels in this population). Suppose
that we have a random sample of 74 children from this population. The sample
mean x = 10.6g/100ml. Estimate a 90% upper confidence limit.
4.
A healthcare company that
specializes in the sterile packaging of disposable gloves has decided to
perform a quality audit of the resistance of a batch of packaged disposable
gloves to the ingress of unsterile air. Out of a batch of 2500 packages, 200
were removed and their sterility examined using the British Pharmacopoeia
sterility tests. The results showed that 35 packages failed the sterility
tests. On the basis of these observations, calculate the 95% confidence limits
for the proportion of defective gloves in the batch (population).
5. If 3 out of 10 mammalian
cell cultures exposed to ultraviolet (UV) radiation developed chromosomal
abnormalities while 9 out of 10 mammalian cell cultures developed chromosomal
abnormalities when exposed to UV radiation plus a common NSAID (nonsteroidal
anti-inflammatory drug).
a)
What type of study design?
b)
Which parameter can determine? Calculate it.
c)
Explain the results.
6. A study was
carried out in Taiwan: a total of 128 histologically or cytologically confirmed
cases of hepatocellular carcinoma and 384 controls without the disease were
included in the study. Of the cases, 77% were carriers of the hepatitis B
surface antigen (HbsAg) compared with only 28% of the controls (Chuang et al., 1992).
a)
Formulate a possible
hypothesis question
b)
What type of study design?
c)
Which
parament can determine? Calculate it.
d)
Explain the results
7. Serum Carotenoids and Risk of
Cervical Intraepithelial Neoplasia in Southwestern American Indian Women (Melissa A. Schiff, Ruth
E. Patterson, Richard
N. Baumgartner, Mary Masuk, Linda van
Asselt-King, Cosette M. Wheeler and Thomas M. Becker,
Published November 2001, Cancer
Epidemiology, Biomarkers & Prevention )
Abstract: «The objective of this research was to evaluate the association
between serum carotenoids and cervical intraepithelial neoplasia (CIN) among
Southwestern American Indian women. Cases were American Indian women with
biopsy-proven CIN II/III cervical lesions (n = 81) diagnosed between November 1994
and October 1997. Controls were American Indian women from the same clinics
with normal cervical epithelium (n = 160). All of the subjects underwent
interviews and laboratory evaluations. Interviews evaluated demographic
information, sexual history, and cigarette smoking. Serum concentrations of
α-carotene, β-carotene, β-cryptoxanthin, lycopene, and lutein/zeaxanthin were
measured by high performance liquid chromatography. Cervical human papillomavirus
infection was detected using a PCR-based test. Increasing levels of α-carotene,
β-cryptoxanthin, and lutein/zeaxanthin were associated with decreasing risk of
CIN II/III. In addition, the highest tertiles of β-cryptoxanthin (odds ratio =
0.39, 95% confidence interval = 0.17–0.91) and lutein/zeaxanthin (odds ratio =
0.40, 95% confidence interval = 0.17–0.95) were associated with the lowest risk
of CIN. In conclusion, specially targeted intervention efforts to increase
consumption of fruits and vegetables may protect Southwestern American Indian
women from developing CIN».
a) Estimate the selection criteria for cases
b) Explain the results of the study using odds ratios
c) Determine the exposure and outcome
8.
Which of the
following health outcomes could be studied using a cross-sectional study
design? Choose all that apply.
a) The prevalence of diabetes among adults in the United
States in 2014
b) The prevalence of diabetes among all patients seen at
a particular health clinic on one day in 2014
c) The number of new cases of diabetes diagnosed among at
risk adults in the United States in 2014
d) The number of people in a population with diabetes who
are obese and the number of people in a population with diabetes who are not
obese, in the United States in 2014
9. A random sample of 1141
men and 1212 women aged 25-64 y (response rate 76%) completed a questionnaire
and underwent a short examination in a clinic. Intake of beer, wine and spirits
during a typical week, frequency of drinking, and a number of other factors
were measured by a questionnaire. The present analyses are based on 891 men and
1098 women who were either nondrinkers or 'exclusive' beer drinkers (they did
not drink any wine or spirits in a typical week). 500 men are beer drinkers and
325 men from this group have the obesity. 80 non-drinkers men are obese.
a) What type of study
design?
b) Which parameters can be
calculated?
c) Determine it and explain
the results.
10. A randomized controlled trial is
conducted to evaluate the incidence of diarrhea in 300 children with otitis
media treated with a broad-spectrum antibiotic, amoxicillin + clavulanic acid,
compared to amoxicillin. During the study, the participants and the
investigator were not aware of the treatment allocation between experimental
and control groups.
This study is:
A. Open-label
B. Single-blinded
C. Double-blinded
D. Non-blinded
The study design described above reduces:
A. Adverse drug reactions
B. Degree of bias
C. Compliance to the study protocol
D. Drop-out rate of participants
E. Duration of the study
Get Free Quote!
450 Experts Online