Block 2 Prev Med Practice and Quiz Problems
A VCOM alumnus wishes to assess patient characteristics in a population. He classifies height as "tall" (above 6 feet) or "Not tall" (6 feet or below). Which of the following levels of measurement best describes the type of data that is being collected? a. Dichotomous b. Interval c. Nominal d. Ordinal e. Ratio
A
A VCOM student measured the height of female medical students in millimeters in a random sample of female medical students across the United States. She viewed her frequency distribution and determined that it was left skewed. Which of the following indicates the relationship of the mean, median, and mode in this distribution? a. Mean < Median < Mode b. Mean > Median > Mode c. Median > Mode > Mean d. Mode < Mean < Median e. Median > Mean > Mode
A
A group of patients with lung cancer is matched to a group of patients without lung cancer. Their history of smoking cigarettes is compared. This is an example of which of the following? a. Case-control study b. Cohort study c. Cross-sectional study d. Longitudinal study e. Randomized controlled trial
A
A researcher stated the null hypothesis and developed an alternative hypothesis based on previous findings in the medical literature. The next step included deciding on a level of significance (alpha level). They want to minimize Type I error. Which of the following significance levels (alpha levels) would help them to minimize the possibility of Type I error the most? a. 0.010 b. 0.050 c. 0.10 d. 0.950 e. 0.990
A
The result of a statistical test, denoted p, shall be interpreted as follows if the significance level (alpha) is set at .05: A. the null hypothesis H0 is rejected if p ≤0.05 B. the null hypothesis H0 is rejected if p> 0.05 C. the alternate hypothesis H1 is rejected if p> 0.05 D. the null hypothesis H0 is accepted if p ≤0.05
A - we reject the null hypothesis if the p value is less than or equal to the alpha level
Beta is the probability of which type of error? a. Type 1 b. Type 2
B
Exam scores of seven pharmacology PhD students are presented (scale range = 0-100 possible points): 20, 79, 80, 81, 85, 88, and 90. For this distribution of scores, which of the following measures of central tendency or dispersion would be least sensitive to the extreme exam score of 20? a. Mean b. Median c. Standard error d. Standard deviation e. Variance
B
Researchers conducted a study to determine the association between occupational exposure to benzene and developing leukemia. One hundred and fifty nurses with leukemia and 250 nurses without leukemia were interviewed to assess exposure to benzene. Twelve of the nurses with leukemia had been exposed to benzene in the past while only 3 of the nurses without leukemia had been exposed. Which of the following values indicates the odds ratio computed for this study? a. 6.67 b. 7.15 c. 8.61 d. 9.09 e. 10
B
Which of the following is the main responsibility of the Institutional Review Board (IRB)? a. Protect the rights and welfare of animals in research b. Protect the rights and welfare of human participants c. Review and approve statistical methodologies d. Review and approve the scientific merit e. To convene only Full Board reviews
B
A researcher wants to examine the effect of a physical activity intervention on weight among grade school children. Fifty students are selected for the study. The researcher takes weight measurements before the intervention and after the intervention. The researcher decides to analyze the amount of weight loss within the group. The data for before the intervention and after the intervention is normally distributed. Which of the following statistical measures is most appropriate to analyze the data? a.Paired t-test b.Two-sample t-test c.Student's t-test d.Kruskal-Wallis Test e.ANOVA
A
A surgeon believes that using traditional surgery technique is actually faster for someone who is fully trained, but faster with the robot for someone who is not fully trained. He measured the two groups and calculated a mean for each group. He wants to test for differences between these two means? Which of the following statistical tests would you most likely use to analyze the data from this study? A.Unpaired t-test B.Chi-square C.Pearson correlation D.Matched pairs t-test E.ANOVA
A
As the alpha level gets lower, which error rate also gets lower? a. Type I b. Type II
A
In a cohort study of frequent flyers, 10 out of 100 passengers who wore masks on their flights and 50 out of 100 passengers who did not wear masks had been diagnosed with COVID-19 by the end of the follow up period. Which of the following values is the most likely relative risk computed for this study? a. 0.20 b. 0.33 c. 0.80 d. 0.40 e. 2.50
A
In a study of chemical workers, 400 workers with respiratory disease and 150 workers without respiratory disease were selected for examination. The investigators obtained a history of exposure to a particular solvent in both groups of workers. Among the workers with the respiratory disease, 250 gave a history of exposure to the solvent, compared to 50 of the workers without respiratory disease. Which of the following study designs best describes this scenario? a. Case control study b. Community trial c. Cohort study d. Cross sectional study e. Comparative clinical trial
A
In the population, there is no difference between men and women on a certain test. However, you found a difference in your sample. The probability (p) value for the data was .03 and you had set your alpha level at .05, so you rejected the null hypothesis. What type of error did you make? a. Type I b. Type II
A
Medical educators compared the mean scores of five schools on a standardized epidemiology exam to determine whether there were any statistically significant differences between them. The data were determined to be normally distributed. Which of the following statistical tests is most appropriate for the medical educators to employ? a. Analysis of variance b. Chi-Square c. Kruskal-Wallis d. Pearson correlation e. t-test
A
We set our alpha level at .05, perform an unpaired t-test for difference of means between two different groups, and obtain a p-value of p = 0.025. What is our next step? A.reject H0 in favor of H1 B.accept H0 and reject H1 C.reject H1 on the basis of this sample D.fail to reject H0 E.cannot decide
A
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. How likely is it that the next patient to come to the office will be a woman or a smoker? a. 0.60 b. 0.20 c. 0.04 d. 0.07 e. 0.02
A is correct. (.50 + .20)-(.50 * .20) = .60 -> Addition Rule of Probability
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. On the frequency distribution showing the number of cigarettes smoked, what is the relationship between the three measures of central tendency? a.The mean, mode, and median will all be at the same point b.The mean will be lower than the median, which will be lower than the mode c.The mean will be higher than the median, which will be higher than the mode d.It is impossible to say from the given information
A is correct. The term "normal distribution" as presented in the vignette is the clue here.
A VCOM student is interested in conducting research using hospital medical records. All records have been de-identified, and the research has been deemed "less than minimal risk". Which of the following levels of IRB review will most likely be conducted? a. Exempt b. Expedited c. Full Board d. No Review e. Translational
B
A VCOM student quantified the relationship between alcohol consumption (as measured in grams) and systolic blood pressure (as measured in mmHg). Tests indicated the measurements of both variables were normally distributed. The student's results indicated that the more grams of alcohol one consumed the higher one's systolic blood pressure. Which of the following statistical tests did this student likely perform? a. Paired t-test b. Pearson correlation c. Spearman's rank correlation d. Unpaired t-test e. Wilcoxon sum rank test
B
A recent study indicated higher incidence of depression in children of mothers who binge drink more than twice per month. If the rate for mothers who binge drink is 25/100,000 and the rate for mothers who do not binge drink is 7/100,000, which of the following values indicates the relative risk for depression in children? a. 0.28 b. 3.57 c. 3.75 d. 18 e. 32
B
A recently published article presented the following results: "5% readmitted to the hospital in the experimental medication group and 12% in the placebo group; adjusted hazard ratio, 0.87; 95% CI, 0.60 to 1.30)". Which of the following statements represents the best interpretation of these findings? a. The absolute risk reduction of 7% is statistically significant b. The authors should fail to reject the null hypothesis c. The authors should the reject null hypothesis and accept the alternative hypothesis d. The finding that readmission to the hospital in the placebo group was higher than in the experimental group was statistically significant e. The point estimate indicates the medication increases the risk of readmission to the hospital
B
You are reading a journal article and you see a p-value of 0.06. According to our 4 Step Approach for Hypothesis Testing, what is our next step? A.No need to investigate any further because the result is not statistically significant. B.Check the alpha level and it compare it to the p-value C. Check to see if they have reported a Type I error D.Check to see if they have reported a Type II error E.Check to see if a parametric or non-parametric tests was performed
B - Once we compute our statistical test and it yields a p-value, we compare it the level of significance (alpha level) that we chose prior to the analysis.
A researcher wishing to demonstrate the efficacy of a new treatment of hypertension compares the effects of the new treatment versus a placebo. This study provides a test of the null hypothesis that the new treatment has not effect on hypertension. He sets the level of significance (alpha) at .05 The statistical test produces a p-value of .06. Based on these findings, what is the most likely decision by this researcher? A.Fail to accept the alternative hypothesis B.Fail to reject the null hypothesis C.Increase the sample size D.Reject the null hypothesis E.Set the alpha to .10
B: P = .06 is greater than alpha set at .05. We fail to reject the null hypothesis. A finding as unusual or more unusual than the one observed in this study could occur by chance 6 out of 100 times. We were only willing to take that risk 5 in 100 times (by setting alpha at .05).
A cohort study that explored the link between flu vaccination and the development of influenza found the following relationship: (RR: 0.30; 95% CI: 0.25. - 0.50). Which of the following statements best represents the Relative Risk Reduction? a. Vaccinated patients contracted influenza at 0.70 times the rate of unvaccinated patients b. Vaccinated patients were 30% less likely to contract influenza than unvaccinated patients c. Vaccinated patients were 70% less likely to contract influenza than unvaccinated patients d. Vaccination is of no benefit to vaccinated or unvaccinated patients e. Vaccination should not be recommended until the confidence interval is narrower
C
A report of a clinical trial of a new drug for herpes simplex II versus a placebo noted that the new drug gave a higher proportion of success than the placebo. The report ended with a statement: chi square = 4.72, p < .05. Which of the following conclusions best represents these findings? a. Fewer than 1 in 20 will benefit from the drug b. If the drug were effective the probability of the reported finding is less than 1 in 20. c. If the drug were ineffective, the probability of the reported finding is less than .05 d. The chance that an individual patient will fail to benefit is less than .05 e. The null hypothesis should not be rejected
C
A researcher claims that he can predict the probability of passing or not passing an exam based on the values of several independent variables including current GPA, hours studied, number of days attending class, and the number of hours of sleep. Which of the following statistical tests is the medical education researcher employing in this study? a. Kendall rank correlation b. Linear Regression c. Logistic regression d. Pearson correlation e. Spearman's rank correlation
C
In a recently published article, the researchers presented the following results: "The annualized rate of depression was 4.5% in the medication group and 6.7% in the placebo group (adjusted hazard ratio, 0.25; 95% confidence interval [CI], 0.11 to 0.52; p<0.0001)." (The alpha level of significance had been set at .01). Which of the following statements represents the best interpretation of these findings? a. Chance accounted for the difference between the groups b.The null hypothesis should not be rejected c. The probability that the difference between the two rates of depression is due to chance is low d. The probability that the difference between the two rates of depression is due to chance is high e. There is not a statistically significant difference between the two rates of depression
C
A group of researchers conducted a study on the efficacy of a new influenza vaccine. Based upon the resulting p-value being lower than the stated alpha level, they concluded that the new vaccine reduced flu rates better than the old vaccine, when in reality, it did not. These researchers have unknowingly committed which of the following types of error? a. 1-B b. Beta c. False Negative d. Type I e. Type II
D
A large study of blood glucose in patients with diabetes revealed a mean of 150 mg/dL and a standard deviation of 10 mg/dL. These data were normally distributed and resulted in a bell-shaped curve. According to these results, 95% of glucose observations in these patients lie between which of the following limits? a. 70 and 230 mg/dL b. 90 and 210 mg/dL c. 110 and 190 mg/dL d. 130 and 170 mg/dL e. 140 and 160 mg/dL
D
A medical educator is interested in the association between the number of books read for leisure per year and GPA among students studying the health professions. These data are considered quantitative, continuous, and normally distributed. Which of the following statistical tests is most appropriate for the researcher to employ? a. Linear regression b. Logistic regression c. Paired t-test d. Pearson correlation e. Spearman's rank correlation
D
A researcher examined the effect of a physical activity intervention on weight among grade school children in 10 different schools. The researcher took weight measurements after the intervention and computed a mean weight for each school. The researchers wants to know if there is a statistically significant difference between the mean weights calculated for the ten schools. Some preliminary tests indicated that the data are not normally distributed. Which of the following statistical measures is most appropriate to analyze the data? a.Paired t-test b.Mann Whitney U c.Logistic Regression d.Kruskal-Wallis Test e.ANOVA
D
A study is conducted to examine the relationship between myocardial infarction and time spent driving when commuting to and from work. One hundred married males who had suffered infarcts were selected and their average commuting time ascertained from either the subject, or if the infarct had been fatal, their spouse. A comparison group of 100 married males who had not suffered infarcts was also selected and their average commuting time recorded. Which of the following measures of association was most likely computed to examine this data for the potential association between commuting time and the occurrence of myocardial infarcts? a. Attributable risk b. Correlation coefficient c. Incidence rate d. Odds ratio e. Relative risk
D
In a study of a new shampoo to promote hair growth, the alpha level was set at 0.05. In a one-tailed test, the new shampoo was compared to a ketoconazole shampoo and the statistical tests produced a p-value of 0.07. The new shampoo increased hair shaft diameter about 2% more than ketoconazole. The side effect profile for both drugs was identical. Which of the following conclusions can be made based on this study? a. The results favor ketoconazole b. The results favor the new shampoo c. The results indicated a statistically significant difference in hair shaft diameter between the two shampoos d. The researchers will most likely fail to reject the null hypothesis e. The researchers will most likely reject the null hypothesis
D
Professor Dumbledore, the head of the Hogwarts School, was interested in the following question: Is the mean study time of the House of Hufflepuff different than the mean study time of the House of Ravenclaw? His null hypothesis was that there is no difference in the mean study time between Hufflepuff and Ravenclaw students. His alternative hypothesis was that Ravenclaw students study more each day. He asked Professor McGonagall to collect from both houses the number of hours that each student studies each day. After collecting data from the two groups, she presented the following data to Professor Dumbledore: the mean for Hufflepuff was 2 hours of study time per day with a standard deviation of 0.5 hours (n =102); Ravenclaw 2.25 hours of study time per day with a standard deviation of 0.7 hours (n=106). Severus Snape conducted the analyses and set the alpha level of significance at .05 He ran an unpaired t-test to test the mean difference of 0.250 and it yielded a p-value of 0.003. Which of the following statements is the best interpretation of the p-value? a. The probability of drawing population means with a difference as unusual as 0.250 when there is no difference in the sample means is 3 in 1000 b. The probability of drawing population means with a difference as unusual as or more unusual than 0.250 when there is no difference in the sample means is 3 in 1000 c. The probability of drawing sample means with a difference as unusual as 0.250 when there is no difference in the population means is 3 in 1000 d. The probability of drawing sample means with a difference as unusual as or more unusual than 0.250 when there is no difference in the population means is 3 in 1000 e. The probability of drawing sample means with a difference as unusual as or more unusual than 0.250 when there is no difference in the sample means is 3 in 1000
D
Yet another group of social epidemiologists conducted a study on level of trust and overall health status using standardized measures. They determined upfront that they wanted to infer their results to the general American population. They collected their sample by using a list of nationwide phone numbers and a computer algorithm to randomly select and dial the numbers. However, in this study, the computer had been programmed to randomly dial certain numbers in a manner that allowed for simple random samples to be taken from several socioeconomic and age groups in proportion to their volume in the total population. Which of the following types of samples was mostly used to recruit patients for this study? a. Cluster sampling b. Non-probability sampling c. Snowball sampling d. Stratified sampling e. Quota sampling
D
We set our alpha level at .01, perform an unpaired t-test for difference of means between two different groups, and obtain a p-value of p = 0.10. What is our next step? A.reject H0 in favor of H1 B.accept H0 and reject H1 C.reject H1 on the basis of this sample D.fail to reject H0 E.cannot decide
D - we fail to reject the null hypothesis because the p value of .10 is greater than our alpha level set at .01
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. How likely is it that two patients who smoke will independently appear in succession in the physician's office? a. 0.20 b. 0.40 c. 0.02 d. 0.04 e. 0.016
D is correct. .20 * .20 = .04 - Multiplication Rule of Probability
A VCOM student wishes to assess birth characteristics in a population. She measures birthweight in grams (in which weight in grams is considered to have an absolute zero --the scale starts at zero grams and goes up). Which of the following variables describes the appropriate measurement scale or type? a. Dichotomous b. Interval c. Nominal d. Ordinal e. Ratio
E
A psychiatrist is studying the effects of escitalopram and duloxetine on Generalized Anxiety Disorder. He administers the Generalized Anxiety Disorder-7 (GAD-7) scale to participants in both groups (those taking escitalopram and those taking duloxetine) and compares the post intervention mean scores. The data from the scale is considered to be interval/ratio level and is determined to be normally distributed. Which of the following statistical test would be the most appropriate for this study? a. Analysis of Variance b. Chi - Square c. Kruskal-Wallis test d. Paired t-test e. Unpaired t-test
E
A psychiatry resident wants to investigate the relationship between stress and burnout during the first year of residency. The resident uses the standardized and well-validated Stress Scale to measures the frequency of stressful events, the impact of these events on residents, the perceived susceptibility and perceived severity of such events, and perceived locus of control. The resident had 60 other residents complete the measure along with completing the Maslach Burnout Scale to determine the presence of burnout. What statistical procedure would help this resident discover if burnout can be predicted from the different aspects of stress that were measured. A.Paired t-test B.Unpaired t -test C.Pearson Correlation D.Chi-Square E.Multiple Regression
E
A researcher wants to examine the effect of a physical activity intervention on weight among grade school children. Fifty students are selected for the study. The researcher takes weight measurements before the intervention and after the intervention. The researcher decides to analyze the amount of weight loss within the group. The data for before the intervention and after the intervention is not normally distributed. Which of the following statistical measures is most appropriate to analyze the data? a.Paired t-test b.Mann Whitney U c.Kruskal Wallis d.Unpaired t-test e.Wilcoxon Signed Rank
E
Approximately how many procedures in medicine do not have an evidence-base to support their use? a. 10% b. 20% c. 25% d. 30% e. 50%
E
For a skewed distribution curve what is the best representation of central tendency? A.Means B.Mode C.Standard Deviation D.Variance E.Median
E
Which of the following is a type of statistical test that uses a contingency table and is used only when there are small samples, having typically a cell count of less than 5. a.ANOVA b.Chi square c.Correlation d.T-test e.Fisher's exact test
E
After reviewing the medical literature, a VCOM student developed a null and alternative hypothesis. Next, she set the level of significance (alpha). According to our 4-step approach, which of the following steps should the student take next? a. Compare the beta level to the p-value b. Compute a p-value c. Compute a test statistic d. Compare the p-value to the alpha level e. Decide to reject or fail to reject the null hypothesis
C
Another group of social epidemiologists conducted a study on level of trust and overall health status using standardized measures. They determined upfront that they wanted generalize their results to the entire American population. They collected their sample by using a list of nationwide phone numbers and a computer algorithm to randomly select and dial the numbers. The researchers indicated that this method may allow them to infer the findings from their sample to the population. Which of the following types of samples was mostly used to recruit patients for this study? a. Cluster sampling b. Non-probability sampling c. Probability sampling d. Snowball sampling e. Quota sampling
C
Comparison of 4 mean exam scores from each of the VCOM campuses. The data are normally distributed. Which of the following tests is most appropriate to compare the means? a. Unpaired t -test b. Chi-square c. ANOVA d. Pearson Correlation e. Paired t -test
C
Several approaches to finding the research/clinical balance have been suggested including which of the following? a. Conduct mainly translational research because its more applicable to patient care b. Engage only residents because students do not have the time to conduct research c. Establish research involving your practice and patients, something you know well d. Select research topics that only add to medical knowledge, separate it from your organization's outcomes e. Work only with the physicians within your practice to focus the research
C
Which of the following drug phases is associated with determining efficacy and the basis for labeling? a. I b. II c. III d. IV e. V
C
Which of the following would have the lower probability of Type I error? A.n = 50 and α = .10 B.n = 50 and α = .05 C.n = 30 and α = .01
C
A psychology major wants to explore the relationship between anxiety and depression using the GAD-7 Anxiety Scale and the PHQ Depression Scale. The distribution of scores is normally distributed. Which of the following statistical tests will the student most likely employ? A.Unpaired t -test B.Paired t-test C.ANOVA D.Pearson Correlation E.Regression
D
Assuming the cutoff for statistical significance is .01 for a given set of data, what is the likelihood for a Type I error to occur? A.5 in 100 B.5 in 1000 C.1 in 1000 D.1 in 100 E.10 in 100
D
A group of social epidemiologists conducted a study on level of trust and overall health status using standardized measures. They asked customers coming out of a Walmart if they would like to participate. In fact, they let anyone who was willing to complete the measures participate in the study. The researchers admitted that they may not be able to infer findings from their sample to a population. Which of the following types of samples was used to recruit patients for this study? a. Convenience sample b. Probability sampling c. Simple random sample d. Stratified sampling e. Systemic sampling
A
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. What is the Z Score corresponding to the number of cigarettes (24) smoked by Mr. Weeknd? a.-2 b.+2 c.0 d.+ 8 e.- 8
B is correct. The Z score corresponds to the number of standard deviations. The mean is 16, standard deviation is 4. Mr. Weekend smokes 24 cigarettes per day which is 2 standard deviations above the mean based on his deviation score of +8.
A researcher wishing to demonstrate the efficacy of a new treatment of hypertension compares the effects of the new treatment versus a placebo. This study provides a test of the null hypothesis that the new treatment has no effect on hypertension. He sets the level of significance (alpha) at .001 instead of .05 because he wants to limit the chance of a Type I error. Which is the most likely result of setting alpha to .001 rather than .05? A.Decreases the chance of a Type II error B.Increases the chance of a Type II error C.Increases the ability to achieve statistical significance D.Increases the power of the study
B: Increases the likelihood of a Type II error. When alpha level is lowered is reduces the chances of Type I error but increases the probability of Type II error. The opposite happens when you raise alpha.
A group of five residents conducted a study that found statistically significant differences between aspirin and ibuprofen for reducing body temperature. They rejected the null hypothesis based on a p-value of .001 that they compared to the alpha level set at .01. Which of the following results most likely would have occurred if they had set alpha at .05? a. Decreased chance of alpha error b. Decreased chance of false positive error c. Increased chance of standard error d. Increased chance of Type I error e. Increased chance of Type II error
D
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. The physician determines the deviation scores for each smoking patient in her sample, squares each of these scores, adds up all the squared scores and then divides them by the number of smoking patients in her sample. The resulting is figure is most likely which of the following? a.Range b.Percentile Rank c.Variance d.Standard Deviation
C is correct. This questions provides the definition of the variance for a sample. See study guide for more information.
The correlation coefficient computed for two parameters measured in 429 patients is r = 0.829. This means that: A. The two parameters are directly correlated, and the link is weak: r is positive and close to 0 B. The two parameters are inversely correlated, and the link is strong: r is negative and close to 1 C. The two parameters are directly correlated, and the link is strong: r is positive and close to 1 D. There are too few cases and we do not trust this coefficient's value
C: the relationship is positive and strong (close to 1)
A VCOM student ran a statistical test that produced a p-value of .01. Prior to the study, she set the alpha level to .05. She wants to increase her chances of detecting a difference if there is one. Which of the following concepts would assist her to increase her chances? a. Decrease the sample size b. Decrease the alpha level c. Decrease effect size d. Increase the sample size e. Decrease power
D
A VCOM student special interest group wishes to assess birth characteristics in a population. They measure birthweight in grams but make sure to report it to the nearest whole gram. Which of the following best describes the type of data reported by the student group? a. Categorical b. Continuous c. Dichotomous d. Discrete e. Ordinal
D
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. A particular patient, Mr. Weeknd, smokes 24 cigarettes per day. What is the corresponding deviation score? a.24 b.40 c.0 d.+8 e.-8
D is correct. Deviation Score = 24[observation] - 16 [mean] = +8 . He smokes 8 more cigarettes per day than the average clinic patient. See study guide for more information on deviation scores.
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. What types of data is formed by the figures the physician has generated regarding the number of cigarettes her patients smoke? a.Nominal b.Ordinal c.Interval d.Ratio e.Continuous
D is correct. It is Ratio because an absolute zero is meaningful. It is also "Discrete" because the doc is counting only the whole number of cigs smoked.
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. If she finds that the variance of the number of cigarettes smokes is 16, what is the standard deviation? a.20 b.36 c.16 d.4 e.0
D is correct. The Standard Deviation is the square root of the Variance and equals 4. The SD is more interpretable than the variance because it is expressed in the original units of measurement.
A family physician is interested in the cigarette use of patients in her practice. She asks all patients who come into her office if they use cigarettes and determines that 20% of her patients smoke. She then asks every third smoker who comes of the office how many cigarettes they smoke each day; she finds that the mean number of cigarettes is 16. She plots the number of cigarettes smoked by each patient on a frequency distribution and finds that it is normally distributed. She also finds the number of male smokers is equal to the number of female smokers. She already knows that half of her patients are men and half are women. Which of the following characteristics of the sample taken by the physician in the above scenario would cause the sample to be biased? a.The fact that the number of cigarettes smoked is normally distributed. b.The fact that systematic samples cannot be representative. c.The fact that the number of male smokers is equal to the number of female smokers. d.The fact that smokers who come to the office are more likely to be sick and perhaps more likely to smoke more cigarettes , than smokers who do not come to the office.
D is correct. This is a general consideration with sampling in all clinics and hospital settings .
Dr. Jones has a family practice and is trying to decide whether to open a gym for his patients. He'll only open the gym and get the machine if he's convinced that more than 50% percent of his patients would join the gym. He plans on taking a random sample of n customers and asking them whether or not they would join the gym. He will set his alpha level at .05 and run a statistical procedure to determine if the sample proportion who say they will join is significantly different from 50%. Which of the following would result in the highest power for this study? A.Sample size of 100 and 50% say they will join B.Sample size of 200 and 50% say they will join C.Sample size of 50 and 60% say they will join D.Sample size of 200 and 65% say they will join
D: It has the largest sample size AND the highest proportion. Increasing the sample size is the most practical and important way to increase the power of a study.
A researcher wishing to demonstrate the efficacy of a new treatment of hypertension compares the effects of the new treatment versus a placebo. This study provides a test of the null hypothesis that the new treatment has not effect on hypertension. He sets the level of significance (alpha) at .01 The statistical test produces a p-value of .001. Based on these findings, what is the most likely decision by this researcher? A.Fail to accept the alternative hypothesis B.Fail to reject the null hypothesis C.Increase the sample size D.Reject the null hypothesis E.Set the alpha to .05
D: P = .001 is less than alpha set at .01. Reject the null hypothesis that the new treatment has no effect on hypertension.
