Epi midterm 2

to the epidemiologist, each of the following is an advantage of utilizing death certificates except A. accuracy and detail of diagnoses listed as underlying causes of death B. available on a continuous basis over many years C. convenient to use D. provide a very high probability the person listed is truly deceased E. inexpensive to use

A. accuracy and detail of diagnoses listed as underlying causes of death

when conducting a proportionate incidence ratio (PIR) analysis of a potential cancer cluster in a defined geographic area in iowa, the most important variable for each cancer case is A. address at time of diagnosis B. full name C. marital status D. race E. social security number

A. address at time of diagnosis

match the following statement with the most appropriate descriptive term: approximately 50% of household contacts of a child who has a common cold become infected A. communicability B. immunogenicity C. incidence D. pathogenicity E. virulence

A. communicability

in a case-control study of the relationship between aspirin and myocardial infarction, controls are matched to cases on the basis of race and gender. this approach to subject selection is intended to decrease the chance of which of the following biases? A. confounding bias B. interviewer bias C. non-response bias D. recall bias E. surveillance bias

A. confounding bias

a secondary household attack rate is most often used to A. estimate degree of communicability of the disease B. estimate prevalence of the disease in young age groups C. estimate role of the environment D. estimate virulence of the disease

A. estimate degree of communicability of the disease

in a case-control study of drinking water contamination as a risk factor for childhood leukemia, mothers cases tend to give more false-positive reports of their child's exposure to contaminated drinking water. the most likely effect on the measure of association from these study findings is A. overestimation B. underestimation C. no effect D. cannot be determined

A. overestimation

alpha or the level of significance corresponds to A. Type I error B. Type II error C. both D. neither

A. type I error

A flu outbreak occurred in a military barracks that housed 40 soldiers. Case A began on May 1st, and Case B on May 2nd. After approximately two weeks, 20 additional cases occurred during approximately a one-week period. No additional cases occurred. Investigators believed these latter cases represent a second incubation period after the occurrence of Cases A and B. What is the secondary attack rate expressedas a percent? A.20/38 * 100 B.20/39 * 100 C.21/39 * 100 D.20/40 * 100 E.22/40 * 100

A.20/38 * 100

A greater than expected number of cases of a disease occurring in a small area or within a short period of time is the definition of A.A cluster B.An attack rate C.Endemic D.Pandemic E.Mixed epidemic

A.A cluster

In a study of 60 cases with myocardial infarction (MI) and 60 controls without MI, blood cholesterol is elevated in 36 cases and 24 controls. From these data the odds ratio is 2.25, indicating that cholesterol is a risk factor that elevates the likelihood of MI 2.25 times. When adjusted for obesity, the odds ratio is 1.28. When stratified by obesity, however, the odds ratio is 1.25 for cases and controls who are obese and1.30 for cases and controls who are non-obese. In this example, obesity is A.A confounding variable B.An effect modifier C.Both D.Neither

A.A confounding variable

Each of the following approaches will help reduce selection bias except A.A standardized protocol for structured interviews B.Development of an explicit case definition C.Enrollment of all cases in a defined time and region D.The use of compensation to encourage high participation

A.A standardized protocol for structured interviews

An investigator examined cases of fetal death in 27,000 pregnancies and classified mothers according to whether they had experienced sexual intercourse within 1 month before delivery. It was found that 11% of the mothers of fetuses that died and 2.5% of the mothers of fetuses that survived had had sexual intercourse during the period. It was concluded that intercourse during the month preceding delivery caused the fetal deaths. This conclusion may be incorrect: A.Because mothers who had intercourse during the month before childbirth may differ in other important characteristics from those who did not B.Because of a failure to achieve a high level of statistical significance C.Because prevalence rates are used when incidence rates are needed D.Because there is no comparison group

A.Because mothers who had intercourse during the month before childbirth may differ in other important characteristics from those who did not

A flu outbreak occurred in a military barracks that housed 40 soldiers. Case A began on May 1st, and Case B on May 2nd. After approximately two weeks, 20 additional cases occurred during approximately a one-week period. No additional cases occurred. Investigators believed these latter cases represent a second incubation period after the occurrence of Cases A and B. Who was the index case? A.Case A B.Case B C.First of 20 additional cases D.Last of 20 additional cases E.None of the above

A.Case A

An outbreak of infectious hepatitis occurred in a fishing community. 110 adult patients with infectious hepatitis and a similar number of healthy adults, selected from the neighborhoods of the patients, were questioned regarding a history of eating raw clams or oysterswithin the preceding 3 months. The study design is best described as A.Case-control study B.Cross-sectional study C.Intervention study D.Prospective cohort study E.Retrospective cohort study

A.Case-control study

In a cohort study of antioxidant intake and protection against lung cancer, smoking is inversely correlated with antioxidant level and positively related to risk of lung cancer. This relationship is most consistent with A.Confounding bias B.Effect modification C.Recall bias D.Selection bias E.Survival bias

A.Confounding bias

In a cohort study of hormone replacement therapy (HRT) and risk of coronary heart disease (CHD), high income level is associated with both HRT and CHD. In this cohort study high income is best classified as representing A.Confounding bias B.Differential misclassification C.Nondifferential misclassification D.Recall bias E.Selection bias

A.Confounding bias

Which of the following data sources is best able to provide numerator data for calculation of incidence of death by gunshot? A.Coroner or medical examiner reports including autopsy reports B.Disease registries C.Hospital discharge survey D.National Health Survey E.Prepaid group practice insurance programs

A.Coroner or medical examiner reports including autopsy reports

The population attributable risk % A.Equals the attributable risk % when the prevalence of exposure is 100% B.Is always greater than the attributable risk % unless the prevalence of exposure is 100% C.Both D.Neither

A.Equals the attributable risk % when the prevalence of exposure is 100%

Each of the following statements about autopsy is true except A.Its performance typically affects the timing of the funeral. B.Its performance typically allows the opportunity to have an open casket at the funeral home. C.Notes and photographs may be taken to document any important findings. D.Small pieces of tissue may be collected for examination under a microscope. E.The body may be x-rayed or scanned to look for problems like fractures, tumors, or gunshot wounds.

A.Its performance typically affects the timing of the funeral.

Usually the highest quality scientific information will come from a case-control or cohort study where A.The hypothesis being tested is specified prior to data analysis, you have good data, and confounders are accounted for B.The hypothesis being tested is specified after data analysis, you have good data, and confounders are accounted for C.The hypothesis being tested is specified prior to data analysis, but you do not have good data

A.The hypothesis being tested is specified prior to data analysis, you have good data, and confounders are accounted for

a study of all women age 20 to 25 years old in a large industrial state found that the annual rate of new cases of cervical cancer in women who used oral contraceptives was 5/100,000 and that it was 2/100,000 in those who did not use oral contraceptives. on the basis of these data, the inference that taking oral contraceptives causes cervical cancer is A. correct B. incorrect because a proportion is used when a rate is required to support the inference C. incorrect because the two groups may differ in other relevant factors D. incorrect due to failure to adjust for possible differences in age distributions of users and non-users E. incorrect due to failure to distinguish incidence and prevalence

C. incorrect because the two groups may differ in other relevant factors

today in the US, the most common manner of death recorded on the death certificate is A. accident B. homicide C. natural D. suicide E. undetermined

C. natural

in a case-control study evaluating mouthwash and risk of oral cancer, the appropriate cases tend to overreport the use of mouthwash. select the most appropriate type of bias A. confounding B. non-response C. recall D. selection E. surveillance

C. recall

In a study of 1000 cases with Disease D and 1000 controls without Disease D, Factor A is elevated in 400 cases and 250 controls. From these data the unadjusted odds ratio is 2.0, indicating that Factor A is a risk factor that elevates the likelihood of Disease D two times. When adjustedfor Factor X, however, the odds ratio is 1.4.When stratified by Factor X, the odds ratiois 2.1 for cases and controls with Factor X as well as 1.0 for cases and controls withoutFactor X. In this example, Factor X is A.A confounding variable B.An effect modifier C.Both D.Neither

C.Both

In statistical tests used in epidemiology, we often find ourselves assuming that we are sampling from a normal distribution with a known variance. In these instances the 95% confidence interval is + or - 1.96 times the standard error. To calculate the standard error you need to know the A.Sample size B.Standard deviation C.Both D.Neither

C.Both

Stratification is used to evaluate A.Confounding bias B.Effect modification C.Both D.Neither

C.Both

A 40-year old man, with a long history of hepatic cirrhosis due to a well-documented history of chronic alcoholism, died in the hospital of slowly progressive liver failure. Autopsy findings included jaundice, micronodular cirrhosis, ascites, and esophageal varices. No hepatocellular carcinoma was identified. What was the immediate cause of death DUE TO or a consequence of? A.Ascites B.Chronic alcoholism C.Cirrhosis of the liver D.Esophageal varices E.Liver failure

C.Cirrhosis of the liver

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

C.Is habitually present in human populations

Statement that some quantity is zero or that no difference exists between two comparison groups. A.Type I error B.Type II error C.Null hypothesis D.Power E.P-value

C.Null hypothesis

Cases of disease divided by total number of infected is the definition of A.Communicability B.Immunogenicity C.Pathogenicity D.Virulence E.None of the above

C.Pathogenicity

The probability of rejecting the null hypothesis when it is false is the definition of A.Type I error B.Type II error C.Power D.P-value E.Confidence interval

C.Power

What would the best source of available information for the incidence of acute leukemia in Iowa? A.Behavior Risk Factor Surveillance System B.Iowa Department of Public Health C.Statewide cancer surveillance program D.Statewide congenital and inherited disorders surveillance program E.None of the above

C.Statewide cancer surveillance program

It has been suggested that physicians may examine women who use birth control more often than or more thoroughly than women who do not. If so, and if an association was observed between a type of birth control and a disease, the association may be due to A.Interviewer bias B.Nonresponse bias C.Surveillance bias D.Survival bias E.Recall bias

C.Surveillance bias

When cause of death information is used for epidemiologic purposes, the data most frequently used are the A.Contributing conditions B.Immediate cause of death C.Underlying cause of death D.A and B E.A, B, and C

C.Underlying cause of death

a study of morality patterns in 20 countries found a positive correlation that was statistically significant (p-value < 0.001) between cigarettes sold per capita and morality rates from cancer of the oral cavity. this finding could be explained by A. cigarette smoking being associated with cancer of the oral cavity B. countries with high cigarette consumption rates having populations that are more susceptible to cancer of the oral cavity for reasons other than smoking C. both D. neither

D. both

to conclude that an observed association between an exposure and disease is internally valid, an investigator should evaluate or reject as alternative explanations for the research findings all of the following except A. bias B. chance C. confounding D. generalizability E. interaction (effect modification)

D. generalizability

match the following statement with the most appropriate descriptive term: febrile respiratory tract infections develop in approximately 80% of children with influenza A.communicability B. immunogenicity C. incidence D. pathogenicity E. virulance

D. pathogenicity

when ranking intervention studies, the study with the best quality would be A. non-randomized with deficiencies in execution or analysis B. non-randomized with good control of confounding; well conducted in other respects C. randomized, but with deficiencies in execution or analysis D. randomized, double-blind, placebo-controlled with sufficient power and appropriately analyzed

D. randomized, double-blind, placebo-controlled with sufficient power and appropriately analyzed

In a study of bone density, each of the following factors requires an increase in sample size to have a confidence interval that does not include the value 1.0 except A.Change the acceptable Type I Error from 0.05 to 0.01 B.Change the acceptable Type II Error from 0.20 to 0.10 C.Change the Power from 80% to 90% D.Decrease the variability in bone density measurement by purchasing a higher quality instrument for measuring bone density E.Narrow the differences you want to detect in bone density between study groups

D.Decrease the variability in bone density measurement by purchasing a higher quality instrument for measuring bone density

In a study of 1000 cases with Disease D and 1000 controls without Disease D, Factor A is present in 400 cases and 250 controls. From these data the unadjusted odds ratio is 2.0, indicating that Factor A is a risk factor that elevates the likelihood of Disease D two times. When adjustedfor Factor X, however, the odds ratio is 2.0.When stratified by Factor X, the odds ratiois 2.0 for cases and controls with Factor X as well as 2.0 for cases and controls withoutFactor X. In this example, Factor X is A.A confounding variable B.An effect modifier C.Both D.Neither

D.Neither

Composite measure that reflects both the magnitude of the difference (variability) between the study groups and the sample size of the study. A.Type I error B.Type II error C.Power D.P-value E.Confidence interval

D.P-value

A flu outbreak occurred in a military barracks that housed 40 soldiers. Case A began on May 1st, and Case B on May 2nd. After approximately two weeks, 20 additional cases occurred during approximately a one-week period. No additional cases occurred. Investigators believed these latter cases represent a second incubation period after the occurrence of Cases A and B. What type of epidemic curve does this outbreak represent? A.Common source epidemic B.Mixed epidemic C.Point epidemic D.Propagative, or progressive, epidemic E.None of the above

D.Propagative, or progressive, epidemic

An outbreak of measles occurred in an elementary school with 300 pupils. During October and November, 72 of the pupils in this school were absent with measles. Prior to this, none of the 300 pupils had ever reported having measles. The 72 pupils with measles had a total of 92 brothers and sisters living at home. Of these siblings, 25 developed measles between October and December.During the 1st week of November, 15 pupils developed measles, 8 on the 1st day of the month. During October, there had been 25 cases, of which 12 still had measles on the1st day of November. Recalling that persons who have had measles are no longer at risk of the disease, 25/92 or 27.2 cases per 100 persons is the A.Attack rate for 1st week in November B.Attack rate for October and November C.Point prevalence on 1st day of November D.Secondary attack rate among siblings E.None of the above

D.Secondary attack rate among siblings

What would the best source of available information for the incidence of cleft lip and cleft palate in Iowa? A.Behavior Risk Factor Surveillance System B.Iowa Department of Public Health C.Statewide cancer surveillance program D.Statewide congenital and inherited disorders surveillance program E.None of the above

D.Statewide congenital and inherited disorders surveillance program

120 persons (80 women, 40 men) became ill following a picnic attended by 240 persons, including 160 women and 80 men. A.The sex-specific attack rate for men was 40/240 or 0.17. B.The sex-specific attack rate for men is less than the overall attack rate. C.The sex-specific attack rate for women was 80/120 or 0.67. D.The sex-specific attack rate for women is equal to the overall attack rate. E.The sex-specific attack rate for women is greater than that for men.

D.The sex-specific attack rate for women is equal to the overall attack rate.

In a study in which all cases of a disease that developed were ascertained, if the relative risk for the association between a factor and the disease is equal to or less than 1.0, then A.Either matching or randomization has been unsuccessful. B.The comparison group used was unsuitable yielding an invalid comparison. C.The factor protects against the development of the disease. D.There is either no association or a negative association between the factor and the disease. E.There is no association between the factor and the disease.

D.There is either no association or a negative association between the factor and the disease.

Cases of severe and fatal disease divided by all cases of disease is the definition of A.Communicability B.Immunogenicity C.Pathogenicity D.Virulence E.None of the above

D.Virulence

in an observational analytic epidemiologic study, the true risk ratio was 2.5, and the study had a bias away from the null hypothesis. the study risk ratio was most likely which of the following: A. 0.5 B. 1.0 C. 2.0 D. 2.5 E. 3.0

E. 3.0

when ranking study designs, the design with the poorest quality would be A. case-control B. case-series C. intervention (clinical trial) D. prospective cohort E. retrospective cohort

B. case-series

the causes of death on a death certificate can be certified by the A. funeral director B. medical examiner or corner C. both D. neither

B. medical examiner or coroner

In a study investigating obesity as a risk factor for breast cancer, the unadjusted odds ratio (measure of association) is 1.5, indicating obesity increases the risk of breast cancer. When adjusted for menopausal status the odds ratio is also 1.5. When stratified by menopausal status, however, the odds ratio is 2.25 for cases and controls who are postmenopausal and 1.00 for cases and controls who are premenopausal. In this example, menopausal status is A.A confounding variable B.An effect modifier C.Both D.Neither

B.An effect modifier

An outbreak of measles occurred in an elementary school with 300 pupils. During October and November, 72 of the pupils in this school were absent with measles. Prior to this, none of the 300 pupils had ever reported having measles. The 72 pupils with measles had a total of 92 brothers and sisters living at home. Of these siblings, 25 developed measles between October and December.During the 1st week of November, 15 pupils developed measles, 8 on the 1st day of the month. During October, there had been 25 cases, of which 12 still had measles on the1st day of November. Recalling that persons who have had measles are no longer at risk of the disease, 72/300 or 24 cases per 100 persons is the A.Attack rate for 1st week in November in pupils B.Attack rate for October and November in pupils C.Point prevalence on 1st day of November in pupils D.Secondary attack rate among siblings E.None of the above

B.Attack rate for October and November in pupils

Each of the following is an approach to handling confounding except? A.Adjustment or standardization B.Blinding C.Frequency matching D.Individual matching E.Stratification

B.Blinding

State Health Registry of Iowa/Iowa Cancer Registry personnel are typically contacted to conduct an initial investigation of a potential cancer cluster through analysis of existing data within the registry. Each of the following data variables is available in the Registry database except A.Address of cancer patient at time of diagnosis B.Cancer screening tests received by cancer patient prior to cancer diagnosis C.Cancer site D.Sex of cancer patient E.Age of cancer patient at diagnosis

B.Cancer screening tests received by cancer patient prior to cancer diagnosis

50 known diabetics, all on insulin therapy, were compared with 50 non-diabetics. The diabetics scored significantly higher on depression based on their responses to a questionnaire (p < 0.005). Which of the following can be ruled out as a viable explanation for this finding? A.Age B.Chance C.Diet D.Insulin therapy E.Other medical therapy

B.Chance

A 40-year old man, with a long history of hepatic cirrhosis due to a well-documented history of chronic alcoholism, died in the hospital of slowly progressive liver failure. Autopsy findings included jaundice, micronodular cirrhosis, ascites, and esophageal varices. No hepatocellular carcinoma was identified. What was the UNDERLYING cause of death? A.Ascites B.Chronic alcoholism C.Cirrhosis of the liver D.Esophageal varices E.Liver failure

B.Chronic alcoholism

Lung cancer prevention is studied in a population of 10,000 smokers who are assigned randomly to receive either a vitamin E pill or a placebo. Which of the following types of studydesign best fits this description? A.Case-control study B.Clinical trial C.Cohort study D.Correlational study E.Cross-sectional study

B.Clinical trial

This past summer questionnaires were mailed to every 10th person listed in a city phone directory. Each person was asked to list age, sex, smoking habits, and respiratory symptoms during the preceding 7 days. Over 90% of the questionnaires were completed and returned. The study design is best described as A.Case-control study B.Cross-sectional study C.Intervention study D.Prospective cohort study E.Retrospective cohort study

B.Cross-sectional study

In cohort studies of the role of a suspected factor in the etiology of a disease, it is essential that A.At the beginning of the study, those with the disease and those without the disease have equal risks of having the factor B.Exposure to the suspected factor occurs prior to the development of disease C.The study group with the factor and the study group without the factor be representative of the general population D.The suspected factor be a risk factor for the disease E.There be equal numbers of persons in both study groups.

B.Exposure to the suspected factor occurs prior to the development of disease

An autopsy requires consent of the family or legal guardian when performed A.For legal reasons B.For medical reasons C.Both D.Neither

B.For medical reasons

Which of the following statements about an epidemiologic cohort study is true? A.External validity is usually not affected by differences between participants and nonparticipants. B.Internal validity is usually not affected by differences between participants and nonparticipants. C.Both D.Neither

B.Internal validity is usually not affected by differences between participants and nonparticipants.

A system that relies on either available data on reportable diseases, or reporting mandated or requested, with the responsibility for the reporting often falling on the health care provider, is know as A.Active surveillance B.Passive surveillance C.Both D.Neither

B.Passive surveillance

A medical examiner is a A.Lay investigator B.Pathologist or other health provider C.Both D.Neither

B.Pathologist or other health provider

Performed when an investigator is able to ascertain the number and types of newly diagnosed cancers among the exposed group (target area) compared with another group (comparison area), but not the structure of the population from which they arose is the definition of A.Direct standardization B.Proportionate incidence ratio C.Proportionate mortality ratio D.Standardized incidence ratio E.Standardized mortality ratio

B.Proportionate incidence ratio

In a study designed to estimate the prevalence of hypertension among adults in an inner-city community, a sample of residents is selected for examination. Which of the following sampling methods is most likely to introduce the least bias? A.Residents living in a random selection of addresses from the phone directory of the community. B.Residents living in a random selection of addresses from the street directory of the community. C.Residents selected randomly from the records of local physicians. D.Residents who respond to a call for volunteers in the community's weekly newspaper.

B.Residents living in a random selection of addresses from the street directory of the community.

In a case-control study of folic acid as a protective factor for spina bifida, mothers of cases tend to give more false-positive reports of folic acid ingestion. The most likely effect on the measure of association is A.Overestimation B.Underestimation C.No effect D.Cannot be determined

B.Underestimation

a survey revealed that of 225 families in which there had been a known case of poliomyelitis, 56 maintained parakeets as a family pet. in another survey, 30 of 99 poliomyelitis patients kept parakeets. the inference that parakeets are a risk factor for poliomyelitis is A. correct B. incorrect because a proportionate ratio is used when a rate is required to support the inference C. incorrect because of failure to distinguish between incidence and prevalence D. incorrect because of failure to recognize a possible cohort phenomenon E. incorrect because there is no control or comparison group

E. incorrect because there is no control or comparison group

occurs when the magnitude of the chosen measure of association between a causal agent and a disease differs according to the level of a third variable A. bias B. chance C. confidence interval D. confounding E. interaction (effect modification)

E. interaction (Effect modification)

in a study of 50 cases and 50 controls, it is determined that the difference found with respect to a possible etiologic factor is not statistically significant. one may conclude from this finding that A. chance or random error is not a possible explanation B. confounding has been eliminated C. observer or interviewer bias has been eliminated D. the lack of statistical significance is solely the result of sampling variation E. none of the above

E. none of the above

in a case-control study of IUD use and risk of ectopic pregnancy, cases are identified from emergency room visits, and the controls are sampled from fertility clinic patients. the most likely type of bias resulting from this aspect of the study is A. confounding B. ecologic fallacy C. misclassification D. recall E. selection

E. selection

match the following statement with the most appropriate descriptive term: death occurs in approximately 20% of cases of pneumoccoccal meningitis A. communicability B. immunogenicity C. incidence D. pathogenicity E. virulance

E. virulence

The National Death Index has mortality data dating back to the A.1930s B.1940s C.1950s D.1960s E.1970s

E.1970s

A 40-year old man, with a long history of hepatic cirrhosis due to a well-documented history of chronic alcoholism, died in the hospital of slowly progressive liver failure. Autopsy findings included jaundice, micronodular cirrhosis, ascites, and esophageal varices. No hepatocellular carcinoma was identified. What was the IMMEDIATE cause of death? A.Ascites B.Chronic alcoholism C.Cirrhosis of the liver D.Esophageal varices E.Liver failure

E.Liver failure

Each of the following is a potential problem with using mortality data for epidemiologic uses except A.Careless certification of the cause of death B.Death information desired is too detailed C.Diagnostic fads D.Incorrect coding of cause of death E.Near universal coverage

E.Near universal coverage

An outbreak of measles occurred in an elementary school with 300 pupils. During October and November, 72 of the pupils in this school were absent with measles. Prior to this, none of the 300 pupils had ever reported having measles. The 72 pupils with measles had a total of 92 brothers and sisters living at home. Of these siblings, 25 developed measles between October and December.During the 1st week of November, 15 pupils developed measles, 8 on the 1st day of the month. During October, there had been 25 cases, of which 12 still had measles on the1st day of November. Recalling that persons who have had measles are no longer at risk of the disease, 27/300 or 9.0 cases per 100 persons is the A.Attack rate for 1st week in November B.Attack rate for October and November C.Point prevalence on 1st day of November D.Secondary attack rate among siblings E.None of the above

E.None of the above

In a study to determine the incidence of chronic disease, 150 people were examined at the end of three-year period. 15 cases were found, yielding an incidence of 10%. 50 other members of the initial cohort could not be examined, the reason being death for 20 of these. What type of bias is represented by this loss of subjects to follow-up? A.Confounding bias B.Effect modification C.Interviewer bias D.Recall bias E.Selection bias

E.Selection bias

A case-control study was carried out in which 120 of 200 cases of stomach cancer and 50 of 200 control subjects gave a history of exposure to radiation. 50% of the cases were men but only 25% of the controls were men. At this point in the study, what is a practical and efficient wayfor you to eliminate differences between cases and controls with respect to sex? A.Age standardization B.Matching C.Randomization D.Restriction of study population E.Stratification

E.Stratification

during an 8-hour work shift at a corporate headquarters building, 100 employees (70 females and 30 males) visited the company's physician with complaints of nausea, vomiting, headaches, and dizziness. all affected individuals responded to supportive treatment and were sent home. in order to search for possible causes of the outbreak, the physician performed an investigation. if 600 employees (300 females and 300 males) worked in the building, then the attack rate among males was A. 0-4% B. 5-9% C. 10-14% D. 15-19% E. 20% or more

C. 10-14%

a confounding variable A. is causally related to (or at least associated with) the disease under study B. is associated with the exposure under study, but is not a result of this exposure C. both D. neither

C. both

usefulness of mortality data as an indicator of disease frequency is more accurate when the disease of interest A. has a high case fatality rate B. is relatively easily diagnosed C. both D. neither

C. both

when applying statistical tests to epidemiologic study data, the p-value reflects A. data variability B. sample size C. both D. neither

C. both

you are interested in assessing the relationship between sample size, level of significance, and power. Sample size requirements are increased by A. changing the level of significance from 0.05 to 0.01 B. changing the power from 80% to 90% C. both D. neither

C. both

the range within which the true magnitude of effects lies with a certain degree of assurance is the definition for A. bias B. chance C. confidence interval D. confounding E. interaction (effect modification)

C. confidence interval