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BIOSTATS QUIZ 6, BIOSTATS Quiz #5, BIOSTATS Q 4, BIOSTATS Q3, BIOSTATS QUIZ2, BIOSTATS Q1, BIOSTATS Quiz #9, BIOSTATS quiz #12
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Terms in this set (98)
Assume researchers are trying to find out the mean concentration levels of a specific drug in a population of individuals' blood during a clinical trail. The researchers find that the sample population has a mean concentration of 6.7 mcg/mL with a standard deviation of 1.3 mcg/mL. Calculate a 95% confidence interval for the mean concentration level of the medication for the population's blood and interpret it.
The researchers are 95.0% confident the true mean concentration of medication in the population's blood is between 4.152 mcg/mL and 9.248 mcg/mL.
Assume a researcher wants to compare the mean Alanine Aminotransferase (ALT) levels in two populations, individuals who drink alcohol and individuals who do not drink alcohol. The mean ALT levels for the individuals who do not drink alcohol is 32 with a standard deviation of 14, and 37 individuals were in the sample. The mean ALT levels for individuals who drink alcohol is 69 with a standard deviation of 19, and 38 individuals were in the sample. Construct and interpret a 95% confidence interval demonstrating the difference in means for those individuals who drink alcohol when compared to those who do not drink alcohol.
The researchers are 95% confident that the true mean difference in ALT values between the population of drinkers and population of non-drinkers is between 24.41 and 39.59.
A researcher has collected the blood samples of 29 individuals and found that the mean hemoglobin concentration for the sample of individuals is 13.9 grams per deciliter and the standard deviation is 1.43 grams per deciliter. Calculate a 95% confidence interval for the mean hemoglobin concentration for the population.
(13.36, 14.44)
A phase three clinical trial for a new medication proposed to treat depression has 1191 participants. If all these individuals are from the group of individuals who were given the medication and 759 individuals who received the medication experienced improvement in their symptoms of depression, construct a 90% confidence interval for the true proportion of individuals on the medication who experienced improvement in their symptoms of depression
(.610, .664)
True or False? Before conducting a confidence interval for the mean difference between two independent samples, a researcher should check to make sure the ratio between both sample's variance is between 0.5 and 2.0.
True
True or False? When calculating a confidence interval for one sample with a continuous outcome and the sample contains 30 or fewer individuals, then a t-score should be used in place of a z-score.
False
True or False? The margin of error for a confidence interval for a population is equivalent to the standard deviation times the z-score value, or t-score value depending on the size of the population, for the probability of interest times the standard deviation of the population.
True
True or False? A researcher compares the BMI of two populations of individuals from different socioeconomic backgrounds and finds that the proportion of individuals considered obese and from a poor background is .37 (n = 112), and the proportion of individuals considered obese and from an affluent background is .27 (n = 87); a 95% confidence interval for the risk difference for obesity among members of the poor population compared to the affluent population is (-0.03, 0.23).
True
True or False? Confidence intervals for relative risks and odds ratios require the usage of the natural log in their formula.
True
Assume a researcher decides to contact individuals by telephone in order to survey them on their consumption of fruits and vegetables and decides to call and survey every 31st individual whose phone number is listed in the phonebook. What type of sampling method best describes the researcher's sampling methodology?
Systematic sampling
Assuming the below results were obtained in a study used to test the accuracy of the rapid diagnostic test for influenza, calculate and interpret the sensitivity of the rapid diagnostic influenza test.
When the rapid diagnostic influenza test is used, 52.22% of individuals who have the flu test positive for the flu.
Assume a cardiovascular surgeon has implanted 13 pacemakers in his patients from a new batch of pacemakers that have been found to have a defect that causes them to stop working. If each pacemaker has a 23.47% chance that it will stop working, which of the numbers below is most close to the probability that all the patients' pacemakers will work the way they are supposed to?
.0527
Assume a researcher wanted to know the probability that an individual's systolic blood pressure would fall below 157 and the researcher found that the z-score corresponding to the 157 systolic blood pressure is 1.62. What is the probability that a random individual's systolic blood pressure would fall below 157?
.9474
Assuming you obtained a random sample of blood glucose levels from 32 individuals from a population and the mean of the population is 120 and the standard deviation of the sample is 15, calculate the probability that the mean blood glucose levels for the sample population will be above 127.
.0041
True or False? If a study utilizes a simple random sampling method, that means each member of the population of interest was equally likely to be selected as a study participant.
True
True or False? Sensitivity and specificity are both forms of conditional probability.
True
True or False? The probability of an individual developing prostate cancer is independent of the sex of the individual.
False
True or False? A clinical trial studying the effects of new antibiotic, which is suspected to be a curative treatment for drug-resistant syphilis, is likely to demonstrate a binomial distribution.
True
True or False? A test used to measure the concentration of inflammatory markers in an individual's blood is being researched. Assuming the test quantifies the concentration of the inflammatory markers in the blood and there are an infinite number of outcome possibilities, a study would likely demonstrate that the inflammatory markers for the population follow a normal or non-normal distribution pattern, depending on the results obtained from the study.
True
Medication for eye pressure release is effective in reducing symptoms in 65% of patients.
If medication is given to 20 glaucoma patients; What is the probability it is effective in 18 or fewer patients?
0.998
Medication for eye pressure release is effective in reducing symptoms in 65% of patients.
If medication is given to 20 glaucoma patients; What is the probability that it is effective in 12 or fewer patients? P(X <= 12)
0.399
Medication for eye pressure release is effective in reducing symptoms in 65% of patients.
If medication is given to 20 glaucoma patients; What is the probability that it is effective in exactly 18 patients?
0.010
Medication for eye pressure release is effective in reducing symptoms in 65% of patients.
If medication is given to 20 glaucoma patients; What is the probability it is effective in more than 18 patients?
0.002
Marital status is best defined as which of the following types of variables?
Categorical variable
A study is being conducted to determine the prevalence of lung cancer in a population and the researchers want to note the frequency of each particular stage of cancer among the members of the population who have lung cancer; in this case the stage of cancer is best defined as which of the following types of variables?
Ordinal variable
A researcher decides to take a random sample of individuals from the population and then track their sugar intake. Assuming the data collected on each individual will be classified into different levels of intake including little to no sugar intake, moderate sugar intake, and high sugar intake, which type of graph would allow the researcher to best represent the data they have collected?
Histogram
Calculate the mean and standard deviation and interpret your findings for the following set of data showing the diastolic blood pressure measurements for a sample of 9 individuals: 61, 63, 64, 69, 71, 77, 80, 81, and 95.
On average, the average distance of an individual data point is approximately 10.93 diastolic pressure points from the mean diastolic pressure of 73.44
What is the median blood glucose level of the following data set collected from 8 individuals: 89, 95, 99, 102, 107, 108, 111, and 119?
104.50
True or False? Bar charts are best used to display the information on data collected from non-measurable qualitative variables.
true
True or False? Box plots are the best way to graphically represent the data obtained from research studies that focus on measuring the outcomes for variables considered to exist on a quantitative continuum.
true
True or False? The standard deviation of any data set is the equivalent of the sample variance of the data set squared.
false; square root
True or False? The mean is the best measure of central tendency for a data set measuring low-density lipoprotein (LDL) in which the individual measures of LDL were 100, 101, 105, 107, 109, 110, and 111.
true
True or False? The best measure of central tendency for a data set containing a high number of single-sided outliers is the mean and the standard deviation.
false; median and IQR
Assuming 320,000 individuals develop Lyme disease each year, what is the attributable risk for the cumulative incidence of Lyme disease that comes from tick bites, if 300,000 of the new cases reported each year come from tick bites?
93.75%
300,000/320,000 X 100%
What statistical property makes odds ratio the ideal measurement for case control studies?
its insensitivity to variance
Longitudinal cohort studies that produce data measured in person-time are particularly subject to which of the following forms of statistical anomaly?
Type one censoring
A disease that has a low prevalence but high incidence is best described as which of the following types of diseases?
A contagious acute illness
A simple random sample of 25,000 individuals are surveyed in order to determine the prevalence of individuals that contracted the flu in the past year. Assuming 4,250 individuals indicated they have been diagnosed with the flu at some point in the past year, what is the prevalence of flu for the past year, as indicated from the survey participants?
17.0%
4,250/25,000 X 100%
TRUE or FALSE? Loss of study participants in longitudinal studies can make estimating the cumulative incidence of a disease more difficult
True
TRUE or FALSE? Relative risk is an ideal form of measurement for a retrospective study design because it allows researchers to recruit both individuals with the outcome of interest and individuals without the outcome of interest, then match individuals from each of the respective groups of individuals of the other group in order to determine if a specific exposure caused the outcome of interest.
False
TRUE or FALSE? An absolute difference calculation is ideal when calculating the risk difference between two categorical variables
True
TRUE or FALSE? A group of 250 women over the age of 40 are recruited for a study to determine the effects that calcium has on bone health. Half of the participants are given a calcium supplement and the other half are given a placebo. If 13 women on calcium develop osteomalacia and 27 women not on the placebo develop osteomalacia, the relative risk for developing osteomalacia for women over 40 on a calcium supplement is 0.48 when compared to those women not taking a calcium supplement. This indicates that taking calcium has no effect on the population of interest's health because the relative risk is less than 1.0.
False
TRUE or FALSE? The public health department in a particular county with 157,237 residents has documented 629 cases of HIV; 157 individuals were diagnosed in the past year. Thus, the cumulative incidence for HIV in this particular county is approximately 0.1.
False
The total number of observation (or records) of this data (the first examination of Framingham Heart Study) is
4434
The number of variable the dataset (first examination of Framingham Heart Study) has is
38
The average age of the study participants in this dataset (the baseline examination of Framingham Heart Study) is about
50 years
Which is true?
Framingham Heart study is a cohort study
Framingham heart study is a cohort study with repeated measurements, which means, some study participants were examined more than once
Framingham heart study is a cross-sectional study
Framingham heart study is a case control study
Framingham heart study is a cohort study with repeated measurements, which means, some study participants were examined more than once
The point prevalence of stroke at the baseline examination of Framingham Heart Study was
7.2/1,000 population
During the study period, the cumulative incidence ratio or risk ratio of CVD between current smokers and non-smokers (assessed at the baseline)
1.0483
The total person years contributed by the smokers (assessed at the baseline survey) in Framingham Heart Study for calculating CVD incidence rate was
?
Mathematically, an odds ratio equate to a risk ratio, therefore, odds ratios can be interpreted in an exactly same way as risk ratio
False
The Framingham Heart Study offers an excellent opportunity to demonstrate the differences between odds ratio and risk ratio in bio-statistic or epidemiologic courses
False
With a large time unit, cumulative incidence is always larger than incidence rate
false
The minimization of bias and confounding in clinical trials is obtained through the use of which of the following?
Randomization of study participants to make groups comparable in all respects
A researcher is interested in determining the current prevalence of rheumatoid arthritis in the United States. Which type of study would be most useful in estimating the prevalence of rheumatoid arthritis in the United States?
A cross-sectional survey
A number of patients have been admitted to a particular hospital with similar symptoms and the cause of the illness is unknown. which type of study design would be most helpful in determining the cause of the illness?
A case series
Misclassification bias is most likely to be observed in which study type?
A case-control study
A novice researcher noted that during summertime there is a positive association between the increase in ice cream, sales and the increase in the number of drownings; however, there is no logical explanation for why ice cream sales would be responsible for the increased incidence of drowning. What phenomenon likely explains this type of observation?
Confounding
True or False? An active-control trial is the best option for researchers hoping to test a newly devised therapy for a life-threatening illness among individuals with the illness, when a previously devised treatment is available for the illness.
True
True or False? The application of treatment among participants in an experimental study is a key difference between an experimental study and an observational study.
True
True or False? Intention-to-treat analysis for a study is only conducted among individuals who fully complied with a study's protocols.
False
True or False? Extremely rare side effects of medications studied in clinical trials are more likely to be observed in cohort studies conducted during post marketing-surveillance because of the limited number of participants in clinical trials.
True
True or False? The wash-out period is included in a crossover trial so that any therapeutic effects of the first treatment are removed, prior to the administration of the second treatment.
True
In the dataset used for SAS pre-screening assessment, how common is the prevalent hypertension among men?
32.46%
In the dataset used for SAS pre-screening assessment, how common is the prevalent hypertension among women?
32.09%
In the dataset used for SAS pre-screening assessment, how common is the current smoking among men?
60.44%
In the dataset used for SAS pre-screening assessment, how common is the current smoking among women?
40.40%
In the dataset used for SAS pre-screening assessment, current smoking was more common in men than in women.
True
A subset of the population of interest is often referred to by
a sample of individuals
The measure of uncertainty in a biostatistician's calculation of a particular outcome that may result from using a subset of the population to estimate the actual likelihood of the event occurring in the population as a whole is referred to by what statistical term?
a margin of error
which of the following most appropriately describes how the data from a cross-sectional study can be applied to a population?
The data generated from a cross-sectional study is only applicable to the original population of interest during the time that the study was conducted
Researchers have conducted a study and determined that the relationship between developing a cold for individuals taking vitamin C is 0.47 when compared to the number of participants in the study who developed a cold while not taking vitamin C. This is an indication of which of the folllowing?
This indicates that the individuals taking vitamin C were 53% less likely to catch a cold and that taking vitamin C has a protective effect, making them less likely to catch a cold
What is the most important factor in determining which populations a well-designed study's results can be applied to?
The inclusion and exclusion criteria for the study
True or False? The data collected in a biostatistics study can be applied to any population regardless of race, class, and socioeconomic status.
False
True or False? Biostatistics is defined as the application of statistics to medicine, public health, or biology.
True
True or False? A relative risk of 5.67 indicates that the group o exposed to the particular variable of interest are 5.67 times more likely the observed outcome being studied
True
True or False? Oftentimes it is more difficult to establish a relationship between a particular disease outcome and a risk factor among older adults because they have other risk factors for disease.
True
True or False? Randomization of clinical trial participants is important to ensure that clinical trail participants in the treatment group and comparator group allow the study's results to be generalized to the population as a whole, and not just the subgroup of individuals that participated in the study because of the balance promoted through the randomization process.
False
True or False? Multiple logistic regression analysis applies when there is a single dichotomous outcome and more than one independent variable.
True
A specific medication used to prevent strokes, heart attacks, and blood clots requires a different dosage of medication for members of the African American population than the Caucasian population because a specific gene affects the way the drug is metabolized within the body. This is an example of which of the following?
Effect modification
A researcher notes that there seems to be a difference in the prevalence of high cholesterol among individuals who smoke and consume diets high in processed food and the prevalence of high cholesterol among individuals who do not smoke and do not consume diets high in processed foods. Use the appropriate hypothesis to test for independence of two independent variables presented here at the 5% significant level to ensure confounding has not influenced the study's results. Then interpret your response.
The chi square value of 37.724 is higher than the chi square value of 3.84, therefore we can reject Ho at the 5% level in favor of H1, which states that smoking status and the amount of processed foods in an individual's diet are not independent of one another.
Research has found that circumcision has a protective effect and helps prevent HIV in men who have sex with women, but circumcision does not seem to have the same protective effect helping to prevent HIV in men who have sex with men. This is an example of which of the following?
Effect modification
A researcher notes that there seems to be a difference in the prevalence of individuals who are medication adherent and have high levels of educations along with a high health literacy and the prevalence of individuals who are not medication adherent and have low levels of education along with a low health literacy. Use the appropriate hypothesis to test for independence of two independent variables presented here at the 5% significance level to ensure confounding has not influenced the study's results. Then interpret your response.
The chi square value of 2577.533 is higher than the chi square value of 3.84, therefore we can reject Ho in favor of H1, which states that an individual's level of education and health literacy status are not independent of one another.
True or False? An r value of -0.3 indicates a weak negative association.
True
A new and relatively expensive medication is released into the population to treat type II diabetes. A doctor notices that poor patients are less likely to see effects from the medication than more wealthy patients, but after conducting a survey the doctor finds the poor patients are less likely to fully comply with their medication regimen because they cannot afford to take the medication on a regular basis. This is an example of which of the following?
Statistical interaction
True or False? Multivariable methods include a number of specific procedure to simultaneously assess the relationships between several exposure or risk factor variables and a single outcome.
True
True or False? a linear regression equation and multiple linear regression equations can be used to calculate y if one is given the x values. However, a logistic regression equation cannot be used to calculate y when one is given x value.
False
True or False? An r value of 0.5 indicates a positive moderate correlation.
True
Which graphic representation could a researcher use to help determine if a continuous variable followed a normal distribution?
Histogram
Which graphic display can be key in communicating complex study protocols?
CONSORT charts
Column titles in a table should describe which of the following?
The grouping variable
Which graph would be most useful in determining the change in two variables over time?
A line chart
Which type of statistical information or graph would be most helpful in determining whether the baseline characteristics of a study group are well balanced?
Descriptive statics
True or False? Using a 95% confidence interval to describe an odds ratio allows other researchers to determine if the results were statistically significant because a statistically significant odds ratio confidence interval will not include the number 1.
True
True or False? The r2 value and a least squares regression line can be an excellent way to demonstrate the degree of correlation between two variabels, and the type of association between the two variables.
True
True or False? Box-whisker plots are useful tools in comparing the mean and the distribution of two or more variables broken down into different categories.
True
True or False? Variable names and units of measurements should be specified clearly and accurately.
True
True or False? Good tables have clear and concise titles.
True
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