Podcast
Questions and Answers
Identify the median in the following list of numbers: 6, 2, 9, 7, 1, 4.
Identify the median in the following list of numbers: 6, 2, 9, 7, 1, 4.
In a study whether Operating room A (OR A) is associated with a higher number of surgical site infections (SSIs) than Operating room B (OR B), the infection preventionist (IP) concludes that the SSI rate in OR A is not equal to the SSI rate in OR B, but in reality, the two rates are equal. What type of statistical error has she committed?
In a study whether Operating room A (OR A) is associated with a higher number of surgical site infections (SSIs) than Operating room B (OR B), the infection preventionist (IP) concludes that the SSI rate in OR A is not equal to the SSI rate in OR B, but in reality, the two rates are equal. What type of statistical error has she committed?
For which of the following procedure(s) is the surveillance period for deep incisional or organ/space SSI 90 days?
For which of the following procedure(s) is the surveillance period for deep incisional or organ/space SSI 90 days?
An appropriate indicator to monitor process compliance would be:
An appropriate indicator to monitor process compliance would be:
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What key infection control activity is defined as the systematic, ongoing collection, management, analysis, and interpretation of data followed by the dissemination of these data to public health programs?
What key infection control activity is defined as the systematic, ongoing collection, management, analysis, and interpretation of data followed by the dissemination of these data to public health programs?
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An IP is reading a journal article that states the data the authors collected are normally distributed. What does this mean?
An IP is reading a journal article that states the data the authors collected are normally distributed. What does this mean?
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Which of the following is indicative of a superficial SSI?
Which of the following is indicative of a superficial SSI?
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What information will be needed to calculate a CLABSI rate for the ICU?
What information will be needed to calculate a CLABSI rate for the ICU?
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What type of rate would the IP want to calculate to give feedback to the surgeons at her facility?
What type of rate would the IP want to calculate to give feedback to the surgeons at her facility?
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The chi-square test can be used:
The chi-square test can be used:
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The measure of central tendency most affected by outliers is:
The measure of central tendency most affected by outliers is:
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In any normal distribution, the proportion of observations that are within two standard deviations of the mean is closest to:
In any normal distribution, the proportion of observations that are within two standard deviations of the mean is closest to:
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The most important feature of nonparametric tests is that they:
The most important feature of nonparametric tests is that they:
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Which of the following indicates a strong positive correlation?
Which of the following indicates a strong positive correlation?
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Which of the following groups is the most appropriate control in a case-control study for infections associated with a health club?
Which of the following groups is the most appropriate control in a case-control study for infections associated with a health club?
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Which of the following steps are not included in hypothesis testing?
Which of the following steps are not included in hypothesis testing?
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The range of the correlation coefficient is:
The range of the correlation coefficient is:
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If the index of kurtosis is -1.99, then the curve is:
If the index of kurtosis is -1.99, then the curve is:
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The probability or likelihood of an event occurring is the:
The probability or likelihood of an event occurring is the:
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A table is used to illustrate data:
A table is used to illustrate data:
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Calculate the mode for the following set of numbers: 2, 11, 5, 21, 3, 11, 8, 26
Calculate the mode for the following set of numbers: 2, 11, 5, 21, 3, 11, 8, 26
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As the sample size increases, how is the power of the study affected?
As the sample size increases, how is the power of the study affected?
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The term for an extraneous variable that systematically varies with the independent variable and influences the dependent variable is a:
The term for an extraneous variable that systematically varies with the independent variable and influences the dependent variable is a:
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When a normal distribution is graphed, which of the following are true?
When a normal distribution is graphed, which of the following are true?
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Which of the following is not considered one of the criteria for causality?
Which of the following is not considered one of the criteria for causality?
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Which of the following are true about a frequency polygon?
Which of the following are true about a frequency polygon?
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Targeted surveillance focuses on:
Targeted surveillance focuses on:
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The number of hand hygiene episodes performed by personnel divided by the number of patient days times 1,000 is a key indicator to assess:
The number of hand hygiene episodes performed by personnel divided by the number of patient days times 1,000 is a key indicator to assess:
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Which of the following viruses is the causative agent in Kaposi's sarcoma?
Which of the following viruses is the causative agent in Kaposi's sarcoma?
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Which of the following is true regarding the epidemiology of coccidioidomycosis?
Which of the following is true regarding the epidemiology of coccidioidomycosis?
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The proportion of a disease that could be prevented by eliminating the exposure in the entire study population can be determined by calculating the:
The proportion of a disease that could be prevented by eliminating the exposure in the entire study population can be determined by calculating the:
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The precision of an estimate of a relative risk depends on which of the following?
The precision of an estimate of a relative risk depends on which of the following?
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The most common reservoir for highly pathogenic avian influenza H5N1 virus is:
The most common reservoir for highly pathogenic avian influenza H5N1 virus is:
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Which of the following is the term for the interrelation of indirect and direct causes of disease?
Which of the following is the term for the interrelation of indirect and direct causes of disease?
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Which of the following statements is true when the prevalence of a disease is very low?
Which of the following statements is true when the prevalence of a disease is very low?
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Which of the following statements regarding the epidemiology of norovirus infection supports this scenario?
Which of the following statements regarding the epidemiology of norovirus infection supports this scenario?
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What is the attributable risk between the exposed and unexposed population in the table?
What is the attributable risk between the exposed and unexposed population in the table?
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Which of the following statements is most accurate regarding the relationship between IBD and CDI?
Which of the following statements is most accurate regarding the relationship between IBD and CDI?
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Which of the following statements about TB and airborne diseases among homeless individuals is most accurate?
Which of the following statements about TB and airborne diseases among homeless individuals is most accurate?
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Which of the following odds ratios is correct in a case-control study examining obesity and Clostridium difficile?
Which of the following odds ratios is correct in a case-control study examining obesity and Clostridium difficile?
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Study Notes
Surveillance and Epidemiologic Investigation Key Concepts
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Median Calculation: The median is the middle value of an ordered data set. For the numbers 6, 2, 9, 7, 1, 4, the ordered set is 1, 2, 4, 6, 7, 9; the median is (4+6)/2 = 5.
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Statistical Errors: A Type I error occurs when the null hypothesis is wrongly rejected, implying a false positive. In the context of surgical site infections (SSIs), if OR A is concluded to have a different SSI rate than OR B when they are actually equal, this is a Type I error.
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SSI Surveillance Period: According to CDC guidelines, the surveillance period for deep incisional or organ-space SSIs is 90 days for procedures like craniotomy and coronary artery bypass graft.
Monitoring Compliance and Indicators
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Process Compliance Indicators: An appropriate indicator for process compliance monitoring is the appropriate antibiotic dosage, which assesses the steps leading to patient outcomes.
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Definition of Surveillance: Surveillance refers to the systematic collection, analysis, and dissemination of health data to improve public health actions.
Statistical Understanding
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Normal Distribution: In a normally distributed data set, the mean, median, and mode are equal. This results in a bell-shaped curve.
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Superficial SSI Criteria: A superficial SSI is identified by symptoms like pain at the incision site and purulent drainage within 30 days post-surgery.
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Calculating CLABSI Rate: To calculate a central line-associated bloodstream infection (CLABSI) rate, one needs the number of identified bloodstream infections and the total device days.
Statistical Tests and Measures
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Chi-Square Test: This test is used to evaluate the association between two categorical variables and requires that each cell in the contingency table has a count greater than 5.
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Influence of Outliers: The mean is significantly affected by outliers, making it less reliable than other measures of central tendency (median and mode).
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P-Value Significance: The p-value indicates the probability of committing a Type I error in statistical conclusions.
Epidemiology Concepts
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Incidence Density Calculation: The incidence density of MRSA infections is calculated by determining the number of infections occurring in relation to patient days in the surgical service.
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Endemic Definition: Endemic refers to an expected number of disease cases in a specific geographic area over time.
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Pandemic vs Epidemic: A pandemic is characterized by its spread across multiple countries or continents, unlike an epidemic that may be restricted to a specific area.
Test Specificity and Data Variability
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Specificity Calculation: The specificity of a test is calculated as the number of true negatives divided by the total number of persons without the disease.
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Measure of Dispersion: The standard deviation and variance measure the dispersion of data around the mean, indicating variability.
Correlation and Hypothesis Testing
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Correlation Coefficient Range: The correlation coefficient (r) ranges from -1 to 1, indicating the strength and direction of a relationship between two variables.
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Hypothesis Testing Steps: Important steps include stating the null and alternative hypotheses, setting significance levels, and comparing probability values, with outlier elimination not being necessary.
Practical Epidemiology
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Control Group in Case-Control Studies: The most suitable control group for a case-control study on infections might be non-ill health club members matched for age and sex.
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Statistical Process Control (SPC) Utilization: SPC charts are used for monitoring processes, identifying variation, and tracking outcomes, but not for eliminating natural variation.### Probability and Risk
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Probability of an event is often referred to as Risk.
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Other related terms include Attack rate, Host factor, and Incidence.
Data Reporting
- Study results should be documented in a report.
- Effective presentation tools include charts or tables.
- Data tables are arranged in rows and columns for clarity.
Statistical Mode
- The mode for the numbers 2, 11, 5, 21, 3, 11, 8, 26 is 11.
Sample Size and Study Power
- As sample size increases, the power of the study is also increased.
Confounding Variables
- An extraneous variable that systematically varies with the independent variable is known as a Confounding variable.
Normal Distribution
- A normal distribution has a continuous, symmetrical curve with both tails extending to infinity.
- The mean, median, and mode are identical.
- Approximately 68.3% of the area lies between the mean and ±2 standard deviations.
- Curve shape is defined by mean and standard deviation.
Causality Criteria
- For an association to imply causality:
- Higher disease incidence in exposed individuals.
- Established relationship between independent and dependent variables.
- Observations of the association across multiple studies.
- The onset of disease must precede exposure.
Frequency Polygon
- A frequency polygon is useful for displaying two sets of data on one graph.
- It employs connecting lines and data points and does not use bars on the x-axis.
Targeted Surveillance
- Focuses on tracking high-risk, high-volume procedures and potentially preventable healthcare-associated infections (HAIs).
Hand Hygiene Reporting
- Hand hygiene adherence can be reported as the number of episodes performed by personnel divided by the number of hand hygiene opportunities by ward or service.
Kaposi's Sarcoma
- The causative agent for Kaposi's sarcoma is Human herpesvirus 8.
Coccidioidomycosis Epidemiology
- Coccidioides spp. are found on the soil surface and are not typically located at high elevations or found in wet climates.
- Up to 50% of individuals in endemic areas may have been exposed to Coccidioides spores.
Attributable Risk Calculation
- To determine the proportion of disease prevented by eliminating exposure, the Attributable fraction needs to be calculated.
Estimate Precision
- The precision of relative risk estimates depends on the size of the study.
Avian Influenza Reservoir
- The primary reservoir for the highly pathogenic avian influenza H5N1 virus is domestic poultry.
Disease Complexity
- The complex interaction among direct and indirect causes of disease is known as a Causal web.
Diagnostic Test Characteristics
- When disease prevalence is very low, the positive predictive value of a diagnostic test is lowered.
Norovirus Epidemiology
- Most outbreaks of norovirus are due to genotype GII.2, and it is the leading cause of epidemic gastroenteritis globally.
Attributable Risk Calculation Example
- Attributable risk can be calculated based on disease outcomes in exposed versus unexposed populations.
IBD and CDI Relationship
- Inflammatory bowel disease is associated with increased morbidity and mortality regarding Clostridium difficile infection (CDI).
Tuberculosis in Homeless Individuals
- Most TB infections among the homeless are reactivations of established diseases, and sputum testing is highly effective.
Odds Ratios in Case-Control Studies
- The odds ratio reflecting the relationship between obesity and Clostridium difficile can be calculated based on provided BMI data.
Studying That Suits You
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Description
Test your understanding of concepts related to the bell curve in statistics. This quiz covers key elements like the proportion of observations within standard deviations and characteristics of nonparametric tests. Challenge yourself with these important statistical foundations!
