W 1 P —30
EEK ROBLEMS POINTS
1. Answer the following matching question.
6 points per problem. Put answers in the following table:
1.
A = A systematic error that introduces uncertainty in estimates of effect or association.
B = A specific type of study involving human participants and randomization to the comparison
group.
C = Complex relationships among variables that can distort relationships between the risk
factors and the outcome.
D = The number of new cases (of disease) over a period of time.
E = A process of organizing comparison groups by similar characteristics.
F = A characteristic that is strongly associated with an reasonably predict whether a person is
likely to develop a disease or not.
G = A design in which subjects are not randomly assigned to treatment.
H = A process whereby participants are partitioned or separated into mutually exclusive or
non- overlapping groups.
I = Incorrect classification of outcome status (case or control) or the incorrect classification of
exposure status.
J = A clinical trial which each participants is assigned to two or more treatments sequentially.
2.= The nested case-control study (type of case-control study) and usually design for a cohort
Study.
3.= The Randomized Controlled Trial (RCT)
4.= C – Cohort Study
5.= A – Randomized Controlled Trial
Term
ABias __3_
BClinical Trial _10
CConfounding __7__
DDisease Incidence __8__
EMatching ___6_
FPrognostic factor _2___
1
2
3
4
5
6
Description
No random assignment
Strongly associated with outcome
Systematic uncertainty
Outcome or exposure classification error
Subjects receive two or more treatments
Creating similar comparison groups
1
1
2
3
4
GQuasi-experimental __1__
HStratification __9__
IMisclassification bias __4__
JCrossover trial ___5_
7Risk factor distortion
8Number of new case of disease over time
9Subjects assigned to non-overlapping groups
10Subject randomly assigned to treatment groups
The analysis will focus specifically on thr association between smoking history and
pancreatic cancer.
Is a cost and time efficient study for studying rare diseases.
Investigators can unsure that a sufficient number of cases are included.
Case-control studies are useful when there are several potentially harmful exposures
under consideration: data can be collected on each exposure and evaluated.
Case-control studies can be subject to bias and confounding. Matching is one way to
handle confounding.
Strengths:
Weaknesses:
Answer the following:
2. An investigator wants to assess whether smoking is a risk factor for pancreatic cancer.
Electronic medical records at a local hospital will be used to identify fifty patients with
pancreatic cancer. One hundred patients who are similar but free of pancreatic cancer will also
be selected. Each participant’s medical record will be analyzed for smoking history. Identify the
type of study proposed and indicate its specific strengths and weaknesses.
Type of study:
3. A study is planned to assess the effect of a new surgical intervention for gallbladder disease.
One hundred patients with gallbladder disease will be randomly assigned to receive either the
new surgical intervention or the standard surgical intervention. The efficacy of the new surgical
The nested case-control study (type of case-control study) and
usually design for a cohort study.
This cohort study involves 100 participants to assess the relationship between
smoking history in participants and pancreatic cancer. In this study are consider
medical records of 50 participants with pancreatic cancer.
Weaknesses:
intervention will be measured by the time is takes a patient to return to normal activities,
measured in days. Identify the type of study proposed and indicate its specific strengths and
weaknesses.
Type of study: The randomized controlled trial (RCT) or Clinical Trial
Strengths:
4. In 1940, 2,000 women working in a factory were recruited into a study. Half of the women
worked in manufacturing and half in administrative offices. The incidence of bone cancer
through 1970 among the 1,000 women working in manufacturing was compared with that of
1,000 women working in administrative offices. Thirty of the women in manufacturing
developed bone cancer as compared to 9 of the women in administrative offices. This study is an
example of a: Answer: c. cohort study
arandomized controlled trial
bcase-control study
ccohort study
dcrossover trial
5. A study is designed to evaluate the impact of a daily multivitamin on students’ academic
performance. One hundred sixty students are randomly assigned to receive either the
multivitamin or a placebo and are instructed to take the assigned drug daily for 20 days. On day
20, each student takes a standardized exam and the mean exam scores are compared between
groups. This study is an example of a: Answer: randomized controlled trial
arandomized controlled trial
bcase-control study
ccohort study
dcrossover trial
1
2
1Ideally in clinical trials should be double blind where neither the investigator nor the
participant is aware of the assigned treatment. However, not always is possible
specifically when consider a trial comparing medical or surgical procedure. This is for
ethical reasons,
Specifically with clinical trial randomized studies, makes more stronger inferences than
with observational studies.
The randomization balance the groups in terms of known and unknown prognostic factors
which minimize confounding
