MidNight Community 2024 PDF

Mid 29 JAN 2024 | 9:00 AM Night Community King Abdul Aziz University, Jeddah 22252 ‫لولا الله ثم تعب وتعاون هذا الفريق لم‬ ‫يكن لُيكتب لهذا العمل الظهور بهذا الشكل‬ ‫عبدالرحمن الحسيني‬ ‫عبدالرحمن زواوي‬ ‫سامح السلمي‬ ‫عبدالملك بركات‬ ‫أمجد شاولي‬...

Mid 29 JAN 2024 | 9:00 AM Night Community King Abdul Aziz University, Jeddah 22252 ‫لولا الله ثم تعب وتعاون هذا الفريق لم‬ ‫يكن لُيكتب لهذا العمل الظهور بهذا الشكل‬ ‫عبدالرحمن الحسيني‬ ‫عبدالرحمن زواوي‬ ‫سامح السلمي‬ ‫عبدالملك بركات‬ ‫أمجد شاولي‬ ‫أحمد باهميم‬ ‫شكًرا لكم‬ ‫محمد سندي‬ ‫‪2024/01/28‬‬  ‫ | فهرس‬Contents Epidemiology | Page 5 Biostatistics | Page 45  ‫اللهم إني أسألك فهم النبيني‬ ‫وحفظ املالئكة املقربني‪،‬‬ ‫اللهم اجعل لساني عامًر ا بذكرك‬ ‫وقلبي بخشيتك‪ ،‬وسري بطاعتك‪،‬‬ ‫إنك على كل شيء قدير‬ ‫وحسبنا اهلل ونعم الوكيل‬  L1 - Introduction to Epidemiology (19 Q’s) 1- The following all contribute to host individual susceptibility, except which? A. Age B. Gender C. Marital status D. Family size E. Nutritional status Ans: D 2- A disease is endemic when: A. Constant over a specific population B. Sporadic in more than one population C. Seasonal over several geographical areas D. Periodic over several geographical areas E. Seasonal over a specific population Ans: A 3- Constant presence of a disease or infectious agent within a given geographic area or population: A. Epidemic B. Pandemic C. Endemic D. Outbreak E. Sporadic Ans: C 4- All of the following are host factors, except which? A. Age B. Gender C. Hygiene conditions D. Family background E. Nutrition Ans: C 5- If 100 cases of cholera were reported in Jeddah, it would be considered as: A. Epidemic B. Endemic C. Outbreak D. Pandemic Ans: C 6- The events in which without the consequence of the disease cannot occur are: A. Enabling factor B. Necessary factor C. Environmental factor D. Host factor E. Sufficiency factor Ans: B 7- An epidemic occurring worldwide or over a very wide area is the definition of: A. Endemic B. Pandemic C. Outbreak D. Sporadic  E. Epidemic Ans: B 8- Occurring irregularly, haphazardly, from time to time is the definition of: A. Endemic B. Pandemic C. Outbreak D. Sporadic E. Epidemic Ans: D 9- All of the following are part of descriptive epidemiology, except which? A. Place B. Association C. Person D. Time Ans: B 10- The British epidemiologist John Snow investigated the distribution of: A. TB B. Malaria C. Cholera D. Hepatitis B E. HIV Ans: C 11-........... is defined as two or more cases that are thought to be linked in the same time and place. A. Epidemic B. Saprodic C. Outbreak D. Pandemic Ans: C 12- All of the following are host factors except: A. Age B. Sex C. Marital status D. Hygiene conditions  E. Family background Ans: D 13- 68-year-old falls in the bathroom counts as what? A. Either Enabling or Sufficient Cause but we aren’t sure B. C. D. Ans: A (Not enough info) 14- Which of the following water-related diseases is a water-hygienic disease? A. Cholera B. Hepatitis C. Conjunctivitis D. Diarrhea E. Typhoid Ans: A (could be B or E) 15- The source of water that is more prone to the transmission of water-borne diseases is? A. Springs B. Seawater C. Shallow Wells D. Rainwater E. Rivers water Ans: C 16- Increased frequency of respiratory infections during winter months is an example of which of the following? A. Cyclical trend B. Pandemic trend C. Seasonal trend D. Secular trend Ans: C 17- Why should an investigator who has no clinical background nonetheless talk to a patient of two as an early step in the outbreak investigation? A. To advise the patient about common risk factors and the usual course of the illness, alter review such information in appropriate reference material  B. To develop hypotheses about the cause of the outbreak C. To verify the clinical findings as part of verifying the diagnosis D. To verify the laboratory findings as part of verifying the diagnosis Ans: B 18- Water-born disease is : A. Cholera B. Schistosomiasis C. HIV D. SARS-2 Ans: A 19- Epidemiology is the study of: A. Distribution and frequency B. Distribution and determinants C. Frequency and determinants D. Research Ans: B  L2 - Morbidity (12 Q’s) 1,2,3- A report on cardiovascular diseases (CVD) in 2012 in a country with 40 million inhabitants was published. At the beginning of the year, there were 30,000 confirmed cases of congestive heart failure (CHF) and during the year, a further 12,000 new cases of CHF were diagnosed. By the end of 2012; 23,000 deaths were registered in the whole country. The underlying cause of death in 4,000 patients was congestive heart failure. 1- What was the incidence rate of CHF per 100,000 persons during the year 2012? A. 10/100,000 B. 30 /100,000 C. 58/100,000 D. 75/100,000 E. 105/100,000 Ans: B 2- What was the prevalence rate of CHF during the year 2012? A. 10/100,000 B. 30 /100,000  C. 58/100,000 D. 75/100,000 E. 105/100,000 Ans: E 3- What was the prevalence rate of CHF at the beginning of 2012? A. 10/100,000 B. 30 /100,000 C. 58/100,000 D. 75/100,000 E. 105/100,000 Ans: D 4- Incidence density differs from cumulative incidence in that it does take into account the following factors, except which? A. Persons who got lost to follow up B. Persons who died C. Persons who entered study later in time D. Persons who developed the outcome under the study E. All the above Ans: D 5- Incidence density is more suitable for all the following, except which? A. Open population B. One-sided closed population C. Semi-open population D. Closed population E. None of the above Ans: B 6- All of the following increase the prevalence of disease, except which? A. Out-migration of healthy people B. Increase in disease duration C. Immigration of healthy people D. Immigration of cases E. Better diagnosis of disease Ans: C 7,8,9- A study was conducted on the relationship between hypertension and IHD. 300 cases have developed IHD from 3,000 hypertensive patients, while 100 cases developed IHD from 5,000 normotensive cases. 7- Find the incidence of IHD among hypertensive patients: A. 15% B. 10% C. 6% D. 8% E. 4% Ans: B 8- Find the incidence of IHD among Non-hypertensive patients: A. 15% B. 3% C. 2% D. 7% E. 4% Ans: C 9- Find the incidence of IHD among the population: A. 5% B. 3% C. 4% D. 7%  E. 8% Ans: A 10- Cumulative incidence is more suitable for: A. Closed population B. Open population C. One-sided closed population D. Semi-open population Ans: A 11- What type of incidence can you use with person-years? A. Odds ratio B. Rate C. Ratio D. Incidence Density Ans: D 12- What type of population do you use with cumulative incidence? A. Closed population  B. Open population C. One-sided closed population D. Semi-open population Ans: A L3 - Mortality (7 Q’s) 1,2,3,4- A report on cardiovascular diseases (CVD) in 2012 in a country with 40 million inhabitants was published. At the beginning of the year, there were 30000 confirmed cases of congestive heart failure (CHF) and during the year, a further 12000 new cases of CHF were diagnosed. By the end of 2012, 23000 deaths were registered in the whole country. The underlying cause of death in 4000 patients was congestive heart failure. 1- What was the all-cause mortality rate per 100,000 in 2012? A. 10/100,000 B. 30 /100,000 C. 58/100,000 D. 75/100,000 E. 105/100,000 Ans: C 2- What was the cause-specific mortality rate from CHF per 100,000 in 2012? A. 10/100,000 B. 30 /100,000 C. 58/100,000 D. 75/100,000 E. 105/100,000 Ans: A 3- What was the case-fatality rate from CHF during the year 2012? A. 1 % B. 3.3 % C. 9.5 % D. 17.4 % E. 25 % Ans: C 4- What was the proportionate mortality rate from CHF in 2012? A. 1 % B. 3.3 % C. 9.5 %  D. 17.4 % Ans: D 5- In the study of heavy smokers, the number of deaths is 57 persons, and the person-year at risk is 25100. The person-year mortality rate/10000 is: A. 22.7 B. 0.227 C. 2.27 D. 18.4 Ans: A 6- Case fertility rate of new coronavirus could be increased due to: A. B. C. D. Ans: No info 7- Long case with data about the population of Wakanda and the prevalence of disease. The question asks about the reason for increased mortality.  E. Population grew older F. Improved healthcare G. Decreased pollution H. Increased Birth rate Ans: A L4 - Types of Study Designs (4 Q’s) 1- The concept of drawing conclusions on an individual level based on results from grouped data is called? A. Effect measure modifier B. Ecological Fallacy C. Selection bias D. Differential misclassification E. Confounding Ans: B 3- Same case of Wakanda, how would you research to find out what they need medically to give it to them?  A. Cross-sectional B. C. D. Ans: A (Not enough info) 4- (Case…) Calculate the prevalence: A. 15 B. 16 C. 18 D. 20 E. 21 Ans: Not enough Info ‫اللهم إنك عفو تحب العفو فاعف عنا‬  L5 – Case-Control (15 Q’s) 1- An epidemiological study was done among 50 cases of IHD and an equal number of normal persons matched by age and sex regarding a history of high fat intake. Among those with IHD, 30 persons consumed a high-fat diet while 40 normal persons consumed a low-fat diet. The type of the previous study design? A. Cross-Sectional Study B. Clinical Trial C. Cohort Study D. Case-Control Study E. Correlational Study Ans: D 2- An epidemiological study was done among 50 cases of IHD and an equal number of normal persons matched by age and sex regarding a history of high fat intake. Among those with IHD, 30 persons consumed a high-fat diet while 40 normal persons consumed a low-fat diet. Which of the following is characteristic of the previous study design? A. The investigator allocates the exposure B. Confounding may affect the study  C. Prevalence rate is the best estimate D. It starts with exposure and looks for the occurrence of the outcome E. Incidence rate is the best estimate Ans: B 3- An epidemiological study was done among 50 cases of IHD and an equal number of normal persons matched by age and sex regarding a history of high fat intake. Among those with IHD, 30 persons consumed a high-fat diet while 40 normal persons consumed a low-fat diet. Calculate the measure of association: A. Odds Ratio which equals 6 B. Odds Ratio which equals 0.375 C. Relative Risk which equals 0.375 D. Attributable Risk which equals 0.42 E. Relative Risk Which equals 6 Ans: A 4- The diseased group tends to remember events associated with the outcome more compared to the control group. Pick the appropriate epidemiological term to describe. A. Confounding  B. Selection bias C. Publication bias D. Interviewer bias E. Recall bias Ans: E 5- People who smoke tend to drink coffee so people who drink coffee tend to have a greater risk of developing lung cancer. What is the appropriate term? A. Selection bias B. Recall bias C. Confounder D. Publication bias E. Recall bias Ans: C 6- Diseased People tend to remember things differently from control groups. This is known as: A. Recall bias B. Confounder C. Interview bias  D. Publication bias E. Selection bias Ans: A 7- A researcher gives gift cards to encourage people to participate in his study. What type of bias is this? A. Recall Bias B. Selection Bias C. Response Bias D. Observer Bias Ans: B 8- 1000 cases of IHD came to the hospital. It was a long case where they took the lipid profile. A. B. C. D. Ans: Either Case-control or cross-sectional. Most likely case-control but we aren’t sure. 9,10,11- A study was designed to investigate whether early exposure to Electromagnetic fields increases the risk of developing leukemia later in life. 205 adults with leukemia and 205 without leukemia were recruited in this study and they were asked about their exposure to electromagnetic fields during childhood. 70 of the cancer patients and 45 of the healthy participants used to live near a source of electromagnetic radiation. 9- The design used in this study is: A. Cohort study B. Case-control study C. Cross-sectional study D. Randomized Controlled Trial E. Retrospective Follow-up study Ans: B 10- All the following procedures may be used to reduce confounding in this study, except: A. Randomization B. Restriction C. Matching for age D. Matching for family history of leukemia E. Multivariate regression Ans: A 11- The measure of association between the exposure and the outcome that can be used in this study is: A. Incidence and equals 0.50 B. The odds ratio and equals 1.18 C. Relative risk equals 1.84 D. The odds ratio equals 1.84 E. Attributable risk 0.12 Ans: D 12- In case-control studies the measure of association between the disease and the exposure is? A. The odds ratio B. The rate ratio C. The exposure odds D. The rate difference E. The attributable risk Ans: A 13- To study the possible association between oral contraceptive use and the occurrence of rheumatoid arthritis (RA), an investigator selected 100 women with confirmed diagnosis of RA and 200 women without RA. Women were then asked about their past use of oral contraceptives. The type of this study is: A. Prospective cohort study B. Retrospective cohort study C. Case-control study D. Cross-sectional study E. Randomized controlled trial Ans: C 14- A case-control study is characterized by all of the following, except which? A. It is relatively inexpensive compared to other epidemiological designs B. Patients with the disease are compared with persons without the disease C. Incidence rates may be calculated directly D. Assessment of past exposure may be biased E. The selection of controls may be difficult Ans: C 15- Measure of association in case-control studies: A. Rate ratio  B. Attributable risk C. Odds ratio D. Incidence E. Relative risk Ans: C L6 – Cohort Study (15 Q’s) 1- What is the measure used in the Framingham heart study: A. Case-Control Studies B. Cohort Studies C. Cross-Sectional Studies D. Case Report Ans: B 2- Follow-up study measure of association: A. Cumulative incidence B. Significance test C. Correlation coefficient  D. Standard deviation E. Relative risk Ans: E 3- Which is false about the cohort study? A. Always prospective B. The measure of association is relative risk C. Can be prospective and retrospective D. Also known as a follow-up study Ans: A 4- All true about cohort study except? A. Useful for rare diseases B. Useful for rare factors C. Loss of follow-up is a limitation of the study D. Multiple exposures can be studied at the same time Ans: A 5- In a study begun in 1975, in City X, a group of 30,000 adults were tested for Hepatitis B positivity. The occurrence of cases of cancer of the liver between 1985 and 1995 was studied in this group. This is an example of a: A. Cross-sectional study B. Cohort study C. Ecological study D. Controlled clinical trial E. Case-control study Ans: B 6- The health authorities are launching a smoking cessation program by designing different activities for smokers. These activities are very expensive but still useful, as a large proportion of lung cancer in the whole population will be eliminated if smoking is stopped. This proportion of lung cancer can be indicated by: A. Incidence B. Relative risk C. Attributable risk fraction among the population D. Attributable risk fraction among smokers E. Odds ratio Ans: C 7- A study found that approximately 85% of cases of schistosomiasis can be prevented by prohibiting children from swimming in the canal. This estimate is an example of? A. An incidence rate B. A relative risk C. A prevalence measures D. An attributable risk E. An attack rates Ans: D 8- In follow-up studies we usually calculate as a measure of association, which one is used? A. The cumulative incidence B. The standard deviation C. The correlation coefficient D. The relative risk E. The significance test Ans: D 9- In the Framingham study (USA), which is still ongoing since 1948, residents who were thirty to sixty-two years of age were enrolled to identify potential risk factors for the occurrence of heart diseases. This is an example of: A. Case-control study B. Cohort study C. Cross-sectional survey D. Ecological study E. Controlled clinical trial Ans: B 10- Several studies have found that approximately 85% of cases of lung cancer are due to smoking. This measure is an example of: A. Incidence B. Positive predictive value C. Relative risk D. Odds ratio E. Attributable risk Ans: E 11,12,13,14- A study was conducted on the relationship between hypertension and IHD. 300 cases have developed IHD from 3000 hypertensive patients, while 100 cases developed IHD from 5000 normotensive cases 11- Find the relative risk: A. 4 B. 3 C. 5 D. 9 E. 11 Ans: C 12- Find the attributable risk: A. 4% B. 6% C. 9% D. 8% E. 10% Ans: D 13- Find the attributable risk among exposed: A. 60% B. 20% C. 90% D. 80% E. 70% Ans: D 14- Find the attributable risk among the population: A. 60% B. 20% C. 90% D. 80% E. 70% Ans: A 15- Measures of height CI A(150-170), CI B(140-180): A. A is narrower and has less variability than B B. B is narrower and has less variability than A C. B is narrower and has more variability than A D. B is wider and has less variability than A  ‫الحمد هلل الذي هدانا لهذا‪،‬‬ ‫وما كنا لنهتدي لوال أن هدانا اهلل‬ Ans: A L7 – Experimental & Secondary Analysis (4 Q’s) 1- Which of the following is the right sequence of the strength of evidence from weakest to strongest: A. Case report > case-control > cohort > RCT > systematic review > meta- analysis B. Cohort > case-control > Case report > systematic review> RCT > meta- analysis C. Systematic review > case-control > Case report > Cohort > RCT > meta- analysis D. Case-control > Case report > cohort > RCT > systematic review > meta- analysis Ans: A 2- Which of the following is not a characteristic of a good clinical trial? A. Randomization B. Allocation concealment C. Controlled D. Non-binding Ans: D 3- In randomized controlled trials we usually calculate as a measure of association: A. The cumulative incidence B. The standard deviation C. The p-Value D. The relative risk E. The odds ratio Ans: D 4- What type of questions are used in an experimental study? A. PICO B. PECO C. PO D. PE Ans: A  L8 - Association & Causation (5 Q’s) 1- The following characteristics describe real association except? A. It describes the population B. Bias is not present C. Chance has been ruled out D. It is always causal E. Confounding might be present Ans: D 2- The degree of statistical relationship between two or more variables is known as? A. Correlation B. Association C. Chance D. Attribution E. Causation Ans: A 3- At autopsy, the pathological lesions within the brains of Alzheimer’s disease patients are shown to contain unusual levels of aluminum. The appropriate criterion is an indicator of? A. Biological plausibility B. Presence of dose-response relationship C. Consistency of results D. Strength of the association E. Correct temporal sequence Ans: A 4- To control for chance effect in epidemiological studies we might resort to? A. Remove confounders B. Apply different statistics C. Take another sample D. Increase the sample size E. Repeat the study Ans: D 5- Which of the following is a criterion of causality: A. Confounding B. Specificity  C. Inconsistency D. Absence of dose-response relationship Ans: B ‫اللهم اجعل ألسنتنا عامرًة بذكرك‪،‬‬ ‫وقلوبنا بخشيتك‪،‬‬ ‫وأسرارنا بطاعتك‪،‬‬ ‫إّنك على كّل شيء قدير‪،‬‬ ‫وحسبنا اهلل ونعم الوكيل‪.‬‬  L1 - Variables & Data (3 Q’s) 1- Weight in kilograms, marital status, and staging of cancer, respectively: A. Nominal, Ordinal, Continuous B. Nominal, Continuous, Ordinal C. Continuous, Nominal, Ordinal D. Ordinal, Nominal, Continuous Ans: C 2- An analysis was done for the races that visited the emergency room 40% were white, 35% were black,20% were native Americans, and 15% were Asians. The best way to be depicted graphically is: A. Histogram B. Pie chart C. Cumulative polygon D. Cumulative frequency curve  E. None of the above Ans: B Note: A nominal variable can only be depicted visually using either bars and columns or pie charts 3- The horizontal axis for a frequency histogram is? A. Class/intervals B. Class mid-point C. Frequency D. Class limit E. Cumulative frequency Ans: A L2 - Measures of Central Tendency (12 Q’s) 1- Mean is 77% and SD is 8%. Find the data at the 84th percentile: A- 80% B- 85% C- 89% D- 88% Ans: B 2- The following data used to graph a box and whisker plot: 6,7,8,9,9,10,11,12,13,14,20 A) Find Q1: A- 8 B- 9 C- 13 D- 11 Ans: A B) Find Q2 (Median): A- 8 B- 13 C- 9 D- 10 Ans: D C) Find Q3: A- 11 B- 12 C- 14 D- 13 Ans: D D) Find IQR: A- 7 B- 5 C- 10 D- 13 Ans: B Note: IQR= Q3-Q1 (To calculate upper whisker, upper-outlier, you multiply the IQR by 1.5 and then add it to Q3)(For lower whisker, you multiply also IQR by 1.5 and subtracts it from Q1) 3- The number of observations in the data considered as an outlier: A- Zero B- 1 C- 2  D- 3 E- 4 Ans: A 4- The number of live births in 5 women are as follows (2,3,6,7,2): A) Find the standard deviation: A- 1.34 B- 5.5 C- 2.6 D- 2.34 Ans: D B) Find the coefficient of variation: A- 0.67 B- 0.58 C- 2.6 D- 0.32 Ans: B C) Find the mean of number of births in this data? A- 3.0 B- 5.5 C- 4.5 D- 4.0 Ans: D D) Find the median for this data? A- 2 B- 6 C- 4 D- 3 Ans: D E) Find the mode for this data A- 2 B- 5 C- 4 D- 3 Ans: A 5- Mean=100 sd=15 calculate the percentile of a person with 85 IQ: A- 84th percentile B- 98th percentile C- 68th percentile D- 16th percentile Ans: D L3 - Normal Distribution (2 Q’s) 1- The number of live births in 5 women are as follows (2,3,6,7,2), Find the standard error of mean: A- 1.6 B- 2.34 C- 1.046 D- 9.0 Ans: C Note: Standard Error of Mean = (SD)/√n 2- If the mean is greater than the median, how would the graph appear? A- Positively skewed. B- Negatively skewed. C- Normally distributed. D- Can not be determined. Ans: A L4 - Confidence interval (4 Q’s) 1- the width of confidence interval is influenced by all of the following factors EXCEPT: A. The sample size B. The desired level of confidence C. The degree of subject to subject variation D. The degree of sample to sample variation E. The distance between the sample mean and the population mean Ans: E 2- The 95% confidence intervals of three drugs for the treatment of high systolic blood pressure are as follows: Drug X (120-130 mmHg), Drug Y (125- 145mmHg) and Drug Z (135-155 mmHg). Which of the following statements is/are correct in lowering systolic blood pressure? A- Drug X is better than Drug Y B- Drug Y is better than Drug Z C- Drug X is better than Drug Z D- Drug Z is better than Drug X E- Both B&C Ans: C 3- To control the effect of chance in epidemiological studies we might resort to A. Remove confounders B. Apply different statistics C. Take another sample size D. Increase sample size Ans: D Note: Remember the confidence interval equation 4- Regarding the table below, which of the following statement is correct: Variable Name RR for Diabetes 95% C.I. BMI 2.75 (0.89-3.25) Family History (FH) 1.75 (1.19-2.34) Jogging 10km/week 0.76 (0.56-0.93) Normal Cholesterol Level 0.65 (0.43-1.06) A. The variable BMI and FH have increased risk B. The variable jogging and Cholesterol have decreased risk C. The variable BMI have higher risk of developing diabetes than FH D. The variable FH and jogging are associated with diabetes Ans: D ‫اللهم وكلت أمري إليك‬ ‫فإنك خري وكيل‬ ‫ودّبر لي أمري‬ ‫فإني ال أحسن التدبري‬  L5 - Statistical Interference (9 Q’s) 1- In a clinical trial conducted to assess the effectiveness of vaccine A & vaccine B, The disease developed in 22 of 90 children who received vaccine A, and developed in 14 of 86 children who received vaccine B, the calculated value = 1.79 & alpha= 0.05, (1)DF=3.84, (2) DF=5.99 Which of the following statistical tests is most appropriate for analyzing this data? A- Chi-square test B- Linear regression test C- Correlation test D- Two-sample T test E- Paired T-test Ans: A 2- In a clinical trial conducted to assess the effectiveness of Vaccine A & Vaccine B. The diseases developed in 22 of 90 children who received Vaccine A and developed in 14 of 84 children who received Vaccine B. If the calculated value= 1.79 & (1) df=3.84, (2) df=5.99. What is the degree of freedom? A- 2 B- 1 C- 3  D- 4 Ans: B Explanation: vaccine A vaccine B for the disease 22 14 for the disease 68 70 total 90 84 =(Number of columns-1)* (number of rows -1) =(2-1)*(2-1)=1 3- Calculate the expected value of the 22 children: A- 18.6 B- 17.59 C- 16 D- 14 Ans: A Explanation: Finding Expected Values During a Chi-Square Test of Independence, Example 178.5 4- You have antihypertensive drug A and drug B. When testing both of these drugs in the same group of patients, what type of test can you use? A- Chi-square test B- Linear regression test C- Correlation test D- Two-sample T test E- Paired T-test Ans: E 5- Disease prevalence between cardiologists and surgeons is what type of test? A- Chi-square test B- Linear regression test C- Correlation test D- Two-sample T test E- Paired T-test Ans: A 6- Statistical significance is achieved when: A- P-value is larger than alpha B- The tabulated value is larger than the calculated value C- Alpha is larger than the P-value  D- Accept the null hypothesis E- Reject the alternative hypothesis Ans: C 7- In a clinical trial conducted to assess the effectiveness of Vaccine A & Vaccine B. The diseases developed in 22 of 90 children who received Vaccine A and developed in 14 of 84 children who received Vaccine B. If the calculated value= 1.79 & (1) df=3.84, (2) df=5.99, Calculate the expected value of the 22 children: A. 18.4 B. 17.59 C. 16 D. 13 Ans: A 8- In a clinical trial conducted to assess the effectiveness of Vaccine A & Vaccine B. The diseases developed in 22 of 90 children who received Vaccine A and developed in 14 of 84 children who received Vaccine B. If the calculated value= 1.79 & (1) df=3.84, (2) df=5.99. What is the degree of freedom? A. 1  B. 3 C. 2 D. 4 Ans: A 9- in a clinical trial conducted to assess the effectiveness of Vaccine A and Vaccine B. The disease developed in 22 of 90 children who received Vaccine A and developed in 14 of 84 children who received Vaccine B. If the calculated value = 1.79 and df= 3.84, what is the degree of freedom A. 1 B. 2 C. 3 D. 4 Ans: A  L6 - Correlation, Regression & Sampling (5 Q’s) 1- The degree of statistical relationship between two or more variables is known as? A. Correlation B. Association C. Chance D. Causation Ans: A Note: - Association is the statistical relationship - ⁠Correlation is testing the strength/degree of association 2- Households are selected randomly, and every person in each household is included in the sample? A. Cluster sampling B. Systemic sampling C. Simple random sampling D. Paired sampling E. Stratified sampling Ans: A 3- A researcher determined the regression equation describing the relationship between the number of years a patient smoked (X) and the extent of lung damage (Y) was Y=11.24+1.31X. What is the predictor extent of lung damage for a patient who has smoked for 30 years? A. 39.3 B. 54.0 C. 30.0 D. 50.5 E. Cannot be determined Ans: D 4- In a study five blocks are selected randomly from 50 homogeneous blocks, 20 households are then selected randomly from each of these five blocks for household interviews. This sampling design is called: A. Cluster sampling B. Systematic sampling C. Simple random sampling D. Non-probability sampling E. Stratified sampling Ans: A 5- Which of the following is called a non-probability sampling? A. Quota sampling B. Cluster sampling C. Systematic sampling D. Stratified random sampling Ans: A L7 - Screening (10 Q’s) 1. The number of people infected with TB and whose screening test was positive is 48. However, the number of people who were not infected with TB and whose screening test was positive is 3 people. Calculate positive predictive value: A. 94% B. 96% C. 54% D. 38% Ans: A 2. The number of people who did not have TB and whose screening test was negative is 47. However, the number of people who were infected with TB and their screening test was negative is 2. Calculate negative predictive value: A. 94% B. 96% C. 44% D. 74% Ans: B 3- Among 1000 persons with negative screening tests for HBV, 900 were not infected. This is? A- Sensitivity A. B. Negative predictive test B. Prevalence C. Positive predictive test D. Specificity Ans: B 4- A screening test to detect Hepatitis C infection was done on a population and it has a sensitivity of 87% and specificity of 90%. If the same screening test was done on drug abusers who have a higher probability of getting Hepatitis C infection, how would validity values differ? A. Specificity: Decrease, PPV: Increase, NPV: Decrease B. Specificity: No change, PPV: Decrease, NPV: Increase C. Specificity: No change, PPV: Increase, NPV: Decrease D. Specificity: Increase, PPV: Increase, NPV: Decrease Ans: C 5- The ability to correctly test those who had the disease: A. Sensitivity B. Specificity C. Positive protective value D. Negative protective value Ans: A 6- Which one of the following best defines the sensitivity of a diagnostic test for a particular disease? A. The difference between the false-positive and false-negative rates. B. A value calculated from the test's specificity.  C. The test's accuracy in correctly identifying patients without the disease. D. The test's accuracy in correctly identifying patients with the disease. Ans: D 7- Screening tests are frequently indicated for diseases that have which of the following criteria? A. The disease has a high mortality risk regardless of early diagnosis B. The disease affects a large proportion of the population with a detectable preclinical phase. C. The course of the disease is poorly understood D. The disease affects most of the population under study with a low morbidity risk Ans: B 8- With regards to the US Preventive Services Task Force, a screening test with grade B evidence suggests that the test has which of the following criteria? A. The test has a moderate benefit with low certainty B. The test has a high benefit with high certainty C. The test has a low benefit with moderate certainty D. The test has a moderate benefit with high certainty Ans: D 9- Which of the following is a unique characteristic of screening compared with diagnostics tests? A. Screening tests are more accurate than diagnostic tests. B. Screening tests form the basis of treatment. C. Diagnostic tests are usually done on apparently healthy individuals. D. Screening tests are less expensive. Ans: D 10- Which study elderly hypertensive that contribute in household in KSA: A. Cluster B. Stratified C. Systematic D. Simple random Ans: A Note: Keyword = household ‫اللهم إني أستودعك ما قرأت‬ ‫وما حفظت‪ ،‬وما تعلمت‪،‬‬ ‫فرده لي عند حاجتي إليه‪،‬‬ ‫إنك على كل شيء قدير‪،‬‬ ‫حسبنا اهلل ونعم الوكيل‬