POPM 3240

An investigator randomly selects 100 old-age homes across Canada and then randomly samples 25% of the residents from each home and tests them for Methicillin-resistant Staphylococcus aureus (MRSA). This is an example of: A. Multistage sampling B. Cluster sampling C. Stratified random sampling D. Systematic random sampling E. Simple random sampling

A

Being totally inspired by our class example of tattoo research, you set out to determine whether there is a difference in tattoo prevalence among Bio Med students and Fine Arts students on campus, and you plan a survey of both populations. Sadly, on the day you did survey, there was a large body ornamentation and tattooing convention in town, and you were told many of the Fine Arts students go to this event every year ("they never miss it!"). Fortunately, the Bio Med students were all on campus and in attendance. You collect what data you can on both populations. Armed with your data, you now want to compare whether the observed difference is statistically significant. Which statistical test should you use? A. Chi-square test B. t-test C. Beta test D. Alpha test E. You could two of the above tests

A

Being totally inspired by our class example of tattoo research, you set out to determine whether there is a difference in tattoo prevalence among Bio Med students and Fine Arts students on campus, and you plan a survey of both populations. Sadly, on the day you did survey, there was a large body ornamentation and tattooing convention in town, and you were told many of the Fine Arts students go to this event every year ("they never miss it!"). Fortunately, the Bio Med students were all on campus and in attendance. You collect what data you can on both populations. Based on the information above, which of the following sources of bias might you be particularly concerned with, and what would be the likely impact on your results A. Selection bias; you would get an underestimate of tattoo prevalence in Fine Arts students B. Selection bias; you would get an overestimate of tattoo prevalence in Bio Med students C. Loss to

A

Clinicians are trying to set up a new blood bank program for patients who need blood transfusions. Obviously, they are very concerned about the potential for contaminated blood entering the blood bank. They decide to use two tests on the donated blood and interpret them together. Which of the following approaches would be best to prevent contaminated blood from entering the bank? A. Interpret the tests in parallel to achieve a higher sensitivity B. Interpret the tests in parallel to achieve a higher specificity C. Interpret the test in series to achieve higher specificity D. Interpret the tests in series to achieve higher sensitivity E. Interpret the tests in series to decrease the sensitivity

A

If you calculate a p-value of 0.176, what do you do? A. Do not reject the null hypothesis B. Reject the null hypothesis C. Do nothing because the p doesn't equal 0.05

A

In a study that is designed to compare two groups, the probability of concluding that the outcomes are different, when in fact they are not different, is considered to be: A. A Type I error B. A Type II error C. Confidence of the study D. Power of the study E. True state of nature

A

Investigators plan to conduct a study to determine whether exercise in primary school children is associated with obesity. To select their study population, they first select a random sample of primary schools in southern Ontario. In each of these schools, they then randomly select 20 students from all of the students in that school to participate in the study. This type of sampling is called: A. Multi-stage sampling B. Cluster sampling C. Convenience sampling D. Systematic sampling E. Simple random sampling

A

Iron-deficiency anemia is medical condition caused by low dietary intake and absorption of iron, and can lead to light-headedness and weakness. An employer is concerned about iron-deficiency anemia and wants to know whether the prevalence of this disease in her employees is different between those employees who take regular lunch breaks and those who do not. Which statistical test should you use to investigate this research objective? A. Chi-square test B. t-test C. Beta test D. Alpha test E. You could use two of the above tests

A

Public health officials keep track levels of antibiotic resistance in enteric bacteria from multiple sources (human, animal, food) with the intention of taking action if changes in the frequency or patterns of resistance are seen. This public health function is best described as: A. Surveillance B. Monitoring C. Built environment D. Health impact assessments E. Emergency preparedness

A

Researchers want to compare rates of chronic obstructive pulmonary disease (COPD) among smokers and non-smokers using medical records. Assume COPD is a disease that can go undiagnosed without unusual medical attention. Also assume that smokers, because they have concerns about the health effects of smoking, seek medical attention to a greater degree than non-smokers. Which of the following biases might be introduced? A. Detection bias B. Confounding bias C. Misclassification bias of the exposure D. Volunteer bias E. Healthy worker effect

A

The cleaning staff of a hospital plays an important role in which of the following prevention strategies? A. Primary prevention B. Secondary prevention C. Tertiary prevention D. Two of the above E. None of the above

A

The time between being exposed to a sufficient cause of disease and the onset of clinical signs is called the: A. Incubation period B. Latent period C. Indemnity period D. Clinical phase E. None of the above

A

When assessing causality, all of the following should be considered, EXCEPT: A. Disease prevalence B. Consistency with other knowledge C. Strength of association D. Alternative explanations E. Biological plausibility

A

You conduct the active surveillance described above, and you estimate a prevalence of 8% with a 95% confidence interval = (5%, 11%). Which of the following statements best describes this confidence interval? A. There is a 95% probability that the actual prevalence falls between 5% and 11% B. There is a 5% probability that the actual prevalence is below 5% C. There is a 95% probability that the actual prevalence would be lower than 5% or higher than 11% D. There is a 95% probability that the actual prevalence is 8% E. More than one of the above is correct

A

You have developed a new test for use in the field, which can be used to determine the presence or absence of ketosis in dairy cattle (a disease of cows that occurs just after calving, and can lead to loss of appetite and other complications). There is not really a gold standard for this disease in the field, and so you compare your results to an existing test that also gives a "yes/no" answer. What measure should you use to evaluate the performance of your new test? A. Kappa B. Intra-class correlation co-efficient C. Simple (linear) correlation D. Sensitivity E. Positive predictive value

A

A research article reports that the prevalence of Staphylococcus aureus in bulk tank milk was 4% based on a sample of dairy cow farms, with a 95% confidence interval of 2.1% to 6.4%. These results indicate which of the following? A. There is a 95% probability that the prevalence is 4% B. There is a 95% probability that the actual prevalence falls between 2.1% and 6.4% C. There is a 95% probability that the actual prevalence would be lower than 2.1% or higher than 6.4% D. There is a 5% probability that the actual prevalence falls between 2.1% and 6.4% E. There is only a 5% probability that the actual prevalence is 4%

B

A researcher conducts a study to determine whether there is an association between diet and obesity in dogs. He samples a group of dogs and determines whether they eat dry or wet food, and also assesses whether or not they are obese. He finds that dogs eating wet food diets are 4 times more likely to be obese than dogs eating dry food. The 95% confidence intervals in this estimate are (0.9, 8.3). Based on this information, you would conclude: A. There is a statistically significant association between diet and obesity in dogs B. There is no significant association between diet and obesity in dogs C. Some dogs are 0.9 times more likely to eat wet food D. Some dogs are 8.3 times more likely to eat dry food E. Without a p-value, it is not impossible to draw any conclusions

B

Academic records were used to confirm students' self-reported grade point averages in a research study. By using this validation process instead of just relying on students' provided responses, the researchers are reducing the likelihood of which of the following? A. Selection bias B. Information bias C. Confounding bias D. Surveillance bias E. None of the above

B

An example of a vector-born disease is: A. HIV/AIDS B. Malaria C. Salmonellosis D. Genital herpes E. Common cold

B

Assume the numbers of Lyme disease cases reported in Canada between 2010-2013 were published by the Public Health Agency of Canada to be: •2010: 128 cases •2011: 132 cases •2012: 140 cases •2013: 139 cases Based on this information, Lyme disease is an example of which of the following disease patterns in Canada? A. Sporadic B. Endemic C. Epidemic D. Pandemic E. Seasonal

B

Endemic means that a disease: A. Occurs clearly in excess of normal expectancy B. Is habitually present in populations C. Affects large number of countries simultaneously D. Exhibits a seasonal pattern E. Is prevalent among animals

B

In Ontario, it is recommended that all women between the ages of 50 and 74 have a mammogram every other year for the early detection of breast cancer. This recommendation is an example of what type of disease prevention? A. Primary prevention B. Secondary prevention C. Tertiary prevention D. Incubation period detection E. Latent period detection

B

In designing a clinical trial to determine whether a new diet is more effective than an old diet in helping achieve weight loss in dogs, an epidemiologist decides to use a power of 90% instead of 80%, to calculate his required sample size. In making this decision, which of the following statements is correct? A. The researcher increases the probability of making a Type II error B. The researcher decreases the probability of making a Type II error C. The researcher increases the probability of making a Type I error D. The researcher decreases the probability of making a Type I error E. B and C are correct

B

One health is not a new concept. Why is the approach particularly applicable to today's critical health issues? A. Humans are living longer lives B. Human populations are growing and people are living in new/different geographic areas C. Global economic disparity D. Vaccination has reduced the incidence of many infectious diseases

B

Percival Pott is most known for which of the following? A. His work on the cholera outbreaks in London, England B. Making one of the first known records of cancer from an occupational exposure C. Conducting one of the first known vaccinations against smallpox using infectious materials from people with cowpox D. Conducting one of the first known randomized controlled trials, exploring treatments for scurvy E. Being anesthesiologist to Queen Victoria during childbirth

B

The local public health department releases a new set of internet memes to help increase the practice of good hand washing in the general public. This represents which level of prevention? A. Pre-Primary B. Primary C. Secondary D. Tertiary E. None of the above

B

The time period between when an animal is exposed to a disease- causing agent and when pathological changes can be detected is known as the _________ period, and interventions instituted at this point are known as __________ interventions. A. Latent, Primary B. Latent, Secondary C. Incubation, Primary D. Incubation, Secondary E. Incubation, Tertiary

B

The use of screening tests to detect diseased individuals has been an integral part of disease control programs. If you are a public health official and your primary concern is to eradicate (i.e. completely eliminate from the population) a specific disease, which of the following would best help to achieve this objective? A. Selection of a test with a high specificity B. Selection of a test with a high sensitivity C. Selection of a test with a low specificity D. Selection of a test with a low sensitivity E. Screening tests cannot be used in disease control programs

B

Which epidemiological term best describes the following statement? "Signs and symptoms of listeriosis can appear from 3 to 70 days after exposure to the bacteria, with a median time of 3 weeks." A. Latent period B. Incubation period C. Communicability period D. Shedding period E. Pathology period

B

Which of the following is FALSE? A. Sub-clinical infection occurs when a pathogen establishes itself in a host, but clinical signs are not visible B. A chi-square test should be used to test whether there's a significant difference in mean values across two populations C. Hand-washing to prevent fecal- oral contamination is a form of primary prevention D. If enough people in a population have been vaccinated, herd immunity can confer protection to non-vaccinated individuals E. A sampling frame is a list of individuals in a source population

B

A clinician has available 2 possible tests that can be used to diagnose disease X. If can individual truly has disease X, it is important that they receive immediate treatment. Fortunately, the treatment does not have negative side effects and so wouldn't cause issues if a truly disease negative individual received treatment. In this scenario, what should the clinician do? A. Use the test with the highest sensitivity B. Use the test with the highest specificity C. Use both tests simultaneously, and use a parallel interpretation D. Use both tests simultaneously, and use a series E. Use both tests simultaneously, and take the average result

C

A researcher sets out to investigate the prevalence of Coxiellosis in sheep farms in Ontario. She believes that flock size may play a role in the disease. She gets a list of all sheep farms in the province and divides them into small, medium, and large flocks. She then randomly samples farms for testing from each group. This describes which sampling approach? A. Simple random sampling B. Convenience sampling C. Stratified random sampling D. Cluster random sampling E. Multistage random sampling

C

A swine producer purchases 1000 young piglets to fill his nursery barn. All of the piglets will be housed together in the same room. He plans to purchase only piglets that have been vaccinated for swine influenza. However, in reality, 3% of the purchased piglets were not vaccinated. Fortunately, none of the unvaccinated piglets become ill with swine influenza. This is an example of: A. Innate immunity B. Acquired immunity C. Herd immunity D. Sporadic disease immunity E. Primary immunity

C

Commonly used techniques to reduce confounding effects include all of the following EXCEPT: A. Matching B. Stratification C. Increasing sample size D. Multivariable regression analysis E. Randomization

C

Edward Jenner is best known for: A. His work on cholera outbreaks in London B. Conducting one of the first randomized controlled trials, exploring treatments for scurvy C. Conducting one of the first vaccinations, for smallpox D. Making one of the first known records of occupational exposures, namely, cancer of the scrotum in chimney sweepers E. Edward Jenner is not known for any of the above

C

Rabies is a disease that can be transmitted from animal to humans, and has a 100% fatality rate in humans. Over the past few decades, efforts to control rabies in wildlife and pets have been quite effective. However, over the past few years, we have seen a large number of cases of rabies in urban wildlife in Hamilton, Ontario area with some spill over into the pet population. Which of the following best describes the current pattern of rabies in Hamilton? A. Sporadic B. Endemic C. Epidemic D. Pandemic E. Latent

C

Researchers investigated parent perceptions of routine childhood vaccinations, like measles, mumps, and rubella (MMR). They found favourable perceptions among 73% of parents surveyed, with a 95% confidence interval of 65% to 81%. These results indicate which of the following? A. There is a 5% probability that the actual prevalence falls between 65% and 81% B. There is a 95% probability that the actual prevalence would be lower than 65% or higher than 81% C. There is a 95% probability that the actual prevalence falls between 65% and 81% D. There is a 95% probability that the prevalence is 73%

C

What is a sufficient cause? A. Any agent that is required for the development of a given disease B. A factor that contributes towards disease causation but is not necessary C. A factor or combination of factors that will inevitably produce disease D. A component cause that is present in any combination of factors that produce disease E. None of the above

C

What would you do, based on these results: RR= 6; 95% CI: 1.1 to 16.7 A. Immediately start drinking 7 cups of coffee a day to increase your chance of good marks by 6 times B. Keep doing what you were doing because the results were not significant C. Wait for another study before jumping to 7 cups of coffee per day D. Eliminate coffee from your diet and switch to green tea

C

When assessing causality, all of the following should be considered, except: A. Temporal sequence B. Strength of association C. Constancy D. P-values E. Dose-response

C

When assessing causality, all of the following should be considered, except: A. Temporal sequence B. Strength of association C. Sufficiency D. Statistical association E. Dose - response

C

When using 2 tests, classifying an individual as positive if they test positive to one, the other, or both tests, is called "_______ testing", and it increases the ________ of the test: A. Series testing, sensitivity B. Series testing, specificity C. Parallel testing, sensitivity D. Parallel testing, specificity E. Long-jump testing, sensitivity

C

Which of the following is NOT a One Health core competency? A. Leadership B. Health Knowledge C. Surgery D. Partnership

C

Which of the following sampling methods would be the best for selecting subjects for a study to determine the prevalence of anthrax exposure (antibodies) in Saskatchewan cattle? A. Convenience sample of cattle closest to the University of Saskatchewan (Saskatoon) B. Random sample of cattle across the province C. Multistage sample of randomly selected cattle farms, and then randomly selected cattle within those farms

C

When epidemiologists judge the evidence to establish possible causes of a health outcome, we consider: A. The estimated strength of association between an exposure and outcome B. Evidence that the exposure of interest appeared befor e the outcome C. Evidence showing that reduction s in the exposure level do not affect the risk of the outcome D. Two of the above E. All of the above

D

Which of the following is FALSE? A. Sub- clinical infection occurs when a pathogen establishes itself in a host, and the host mounts an immune response but does not show clinical signs B. A t-test should be used to test whether there is a significant difference in mean values across two populations C. Condom use is a form of primary prevention D. A target population is the population we enroll in our study E. Herd immunity can confer protection to individuals who are unable to mount an immune response themselves

D

Which of the following is NOT a core public health system function in Canada? A. Disease and injury prevention B. Health promotion C. Health protection D. Individual health assessment E. Population health assessment

D

Which of the following statements is CORRECT? The p-value gives the probability of: A. Obtaining a result as, or more, extreme than the one observed B. The null hypothesis arising by chance alone C. The null hypothesis being true D. The observed results arising if the null hypothesis is true E. More than one of the above is correct

D

You are working for Public Health Ontario, and are helping design a research study to do active surveillance for listeriosis in a high- risk population. You expect the prevalence of listeriosis in this population to be 5%. You want your prevalence estimate to have a precision of +/- 2% and 95% confidence. The minimum required sample size for your study is: A. 10 B. 91 C. 233 D. 457 E. 4,562

D

You have come into some money, and have decided that you would like to buy some horses, because they bring you much joy. You have heard about Equine Infectious Anemia, a serious viral disease of horses, so you want to test the horses before purchase to avoid buying sick horses. Given your concerns, you decide to use two tests on the horses and interpret them together. Which of the following approaches would be best for you to use? A. Interpret the tests in series to achieve higher sensitivity B. Interpret the tests in series to decrease the sensitivity C. Interpret the test in series to achieve higher specificity D. Interpret the tests in parallel to achieve a higher sensitivity E. Interpret the tests in parallel to achieve a higher specificity

D

You set up a food safety program with Public Health Ontario to test all cheeses and other foods commonly associated with listeriosis to ensure that no Listeria contaminated food is brought into this high- risk population. Given this objective, and assuming the use of multiple food safety tests in combination, which of the following approaches would be best for you to use? A. Interpret the tests in series to achieve higher sensitivity B. Interpret the tests in series to decrease the sensitivity C. Interpret the test in series to achieve higher specificity D. Interpret the tests in parallel to achieve a higher sensitivity E. Interpret the tests in parallel to achieve a higher specificity

D

Zika virus is a flavivirus that can be transmitted to humans via mosquitoes and can cause headaches, rashes, fever, and joint pain. There is evidence that newborns of mothers who were infected with Zika virus during the first trimester of pregnancy may risk brain damage due to the infection crossing the placenta. Zika Disease has been known to occur since the 1950s, but in April 2015, large numbers of cases were observed in Brazil, and now the disease has spread to large parts of South and Central America, as well as the Caribbean. Based on the above information, Zika Disease is an example of which of the following disease transmission patterns? A. Vector-borne B. Vertical transmission C. Aerial transmission D. Two of the above E. All of the above

D

an investigator randomly selects 2000 different households in Guelph, then visits each to find out what each person in those homes had to eat the previous day so he can draw conclusions about all people in Guelph. This is an example of: A. Simple random B. Systematic sampling C. Stratified random sampling D. Cluster sampling E. Multistage sampling

D

A researcher sets out to investigate the prevalence of Porcine Respiratory and Reproductive virus amongst pig farms in Ontario. She gets a list of all pig farms from Ontario Pork, and then uses a random number generator to randomly select 100 farms. She then randomly samples 20% of all pigs on each of the 100 farms and collects the specimens for testing. This describes which sampling approach? A. Simple random sampling B. Convenience sampling C. Stratified random sampling D. Cluster random sampling E. Multistage random sampling

E

In designing a clinical trial to determine whether a new canine diet is more effective than an old diet in helping achieve weight loss in dogs, an epidemiologist decides to use a power of 70% instead of 80%, to calculate his required sample size. In making this decision, which of the following statements is correct? A. The researcher increases the probability of making a Type II error B. The researcher decreases the probability of making a Type II error C. The researcher will need a larger sample size for the study D. The researcher will need a smaller sample size for the study E. A and D are correct

E

You own a sheep farm (lucky you!) and want to increase your flock size to meet the growing demand for lamb in Ontario. You decide to purchase sheep from a nearby producer who is retiring. Being smart, you want to test his sheep first, so that you do not introduce Johne's disease to your existing flock. Two tests are available. Which approach would be best in this scenario? A. Use the one test with the higher sensitivity B. Use the one test with the higher specificity C. Use two tests, and interpret them in series to achieve higher sp ecificity D. Use two tests, and interpret them in series to achieve higher sensitivity E. Use two tests, and interpret them in parallel to achieve higher sensitivity

E

Zika Disease is an example of which of the following disease temporal patterns? A. Seasonal B. Sporadic C. Endemic D. Epidemic E. Pandemic

E

A medical company has developed a new test for antibodies to the Ostertagia ostertagi parasite, and wants to know how well it compares with their competitor's test. They calculate the Kappa statistic. How can Kappa help the company make a decision? A. It cannot help, because statistical tests cannot be used to compare medical tests B. It cannot help, because you need a gold standard to compare tests C. It can help by showing which tests performs better D. It can help by providing an indication of how well the tests agree beyond chance E. It can help by providing an indication of the sensitivity of the tests when used together

D

Based on the historical epidemiological approaches discussed in this course, which of the following statements are true? A. It is necessary to know the causative agent (i.e., the specific virus, bacteria, or parasite) to implement effective control measures B. Understanding the spatial distribution of cases and non-cases of disease can provide clues as to the possible causes of that disease C. Some diseases may be caused by occupational exposures D. B and C

D

In a research study, daycares were selected at random, and every child in each daycare was included in the sample. This best describes which type of sampling method? A. Simple random sampling B. Systematic random sampling C. Stratified random sampling D. Cluster sampling E. Multistage sampling

D

James Lind is most known for which of the following? A. His work on the cholera outbreaks in London, England B. Making one of the first known records of cancer from an occupational exposure C. Conducting one of the first known vaccinations against smallpox using infectious materials from people with cowpox D. Conducting one of the first known randomized controlled trials, exploring treatments for scurvy E. Being anesthesiologist to Queen Victoria during childbirth

D

Newborn infants have a greater than 10% chance of being born with hepatitis B if their mother is infected with this virus. What type of transmission does this represent? A. Direct contact transmission B. Indirect contact transmission C. Vector transmission D. Vertical transmission E. Host-agent transmission

D

Public Health Ontario reports that the annual number of cases of listeriosis for the years 2009 to 2015 ranged between 43 and 65 (average: 53 cases); however, in 2016, 96 cases were reported. Which of the following disease patterns is most consistent with this description? A. Yearly B. Sporadic C. Endemic D. Epidemic E. Pandemic

D

The numbers of cases of Superfragililicosis in Canada over the last 5 years were published by the Public Health Agency of Canada as: •2012: 222 •2013: 227 •2014: 203 •2015: 213 •2016: 2,143 Based on this information, the temporal pattern that best describes Superfragililicosis in 2016 is: A. Seasonal B. Sporadic C. Endemic D. Epidemic E. Pandemic

D

The time between being exposed to a sufficient cause of disease and being able to detect that disease state once it's under way is called the: A. clinical phase B. indemnity period C. incubation period D. latent period E. sufficient exposure

D