CIC Surveillance & Epi Investigation Practice Questions

Which measure of central tendency is least affected by outliers?

Median

Statistical process control (SPC) charts are used for:

Monitor process of care Facilitate the determination of variation Monitor outcomes

The range of the correlation coefficient is:

-1 to 1

What is the probability of committing a Type I error if the p value is 0.10?

1 in 10

The steps of hypothesis testing include:

1. State the research question 2. Specify the null & alternative hypothesis 3. Calculate test statistic 4. Compute the probability of test statistic or rejection region 5. State conclusions

To meet the criteria for a superficial SSI, the infection must occur within ____ days after the operation and involve only ________ or _______ tissue.

30 days; skin or subcutaneous tissues

On September 1, there were 30 surgical patients in the hospital. Two of these were postop patients with SSIs. A total of 75 surgeries were performed in September. Six additional SSIs occurred in patients who had surgery in September. What was the numerator for an incidence rate in September?

6

Hill's Criteria - Associations derived from experiments that help add weight to evidence supporting causal association.

Analogy

The difference in rate of a condition between an exposed population and an unexposed population is called:

Attributable risk

A calculation that can be derived from the attributable risk, which is the difference in rate of a condition between an exposed population and an unexposed population is:

Attributable risk percent (ARP)

Hill's Criteria - A dose-response relationship between increased exposure to a factor and increased likelihood of disease. For example, the longer one smokes, the more likely one is to develop lung cancer.

Biological gradient

Indirect and direct causes of disease may form a complex network of events that determines the level of disease in a community known as:

Causal web

Hill's Criteria - The association should be in accordance with other facts known about the natural history of the disease.

Coherence

An extraneous variable that systematically varies with the independent variable and influences the dependent variable is a:

Confounding variable

Hill's Criteria - the association should be observed in numerous studies, preferably by different researchers using different research methodologies.

Consistency

For which procedures is the surveillance period for deep incisional or organ space SSI 90 days?

Craniotomy, CABG

Hypothesis testing estimates the likelihood or probability that a result:

Did not occur by chance

The most common reservoir for highly pathogenic avian influenza H5N1 virus is:

Domestic poultry

The chi-square test can be used to/if:

Evaluate the effect of a variable on outcomes Calculate an odds ratio or relative risk IF each cell of the table is >5

Which statistical test is used when the data are small in numbers?

Fisher's exact

A statistical significance test used in the analysis of contingency tables that is valid for all sample sizes:

Fisher's exact test

Which virus is the causative agent in Kaposi's sarcoma?

Human herpesvirus 8

Attributable Risk (AR) formula

Incidence exposed - incidence unexposed

An outbreak of norovirus in an LTCF would most likely have an epidemiological curve (EPI curve) that:

Indicated a propagated source

A propagated source means:

Infections are transmitted from person to person in such a way that cases identified cannot be attributed to agent(s) transmitted from a single source. Propagated (continuing) source cases occur over a longer period than in common source transmission.

A frequency polygon...

Is useful for showing 2 sets of data on a single graph Uses connecting lines and data points

The most important feature of nonparametric tests is that they:

Make no assumptions about variance in populations

The measure of central tendency most affected by outliers is:

Mean

What symptoms are indicative of a superficial SSI?

Pain at the incision site 10 days after breast reduction with drainage positive for MSSA

Hill's Criteria - The association should be biologically sound in light of current knowledge. Lack of this does not disprove association

Plausibility

The IP wishes to know the proportion of a disease that could NOTES be prevented by eliminating the exposure in the entire study population. In order to determine this information, the IP will need to calculate the:

Population attributable risk percent

As the sample size increases, how is the power of the study affected?

Power is INCREASED

If the index of kurtosis is -1.99, then the curve is:

Relatively flat

Which of the following quality concepts will identify a pattern of observation points above and below the mean level?

Run chart

The power of a hypothesis test is affected by:

Sample size (higher sample size = greater power) Significance level (higher significance = higher power) The "true" value of the parameter being tested (the greater effect size = greater power)

When dealing with TB in the homeless population:

Screening for TB with a chest x-ray may be the most cost effective approach

The precision of an estimate of relative risk depends on:

Size of the study

Hill's Criteria - Refers to an association between one factor and one disease, and this association is more likely to be causal. This criterion also refers to the extent to which the occurrence of one factor can be used to predict the occurrence of another (disease).

Specificity

A measure of dispersion that reflects the variability in values around the mean is called:

Standard deviation

When benchmarking data to other facilities, the IP should analyze the entire process to ensure what conditions are met?

Standardized definitions are used consistently Adequate training of personnel to collect, store, manage, and analyze data Data are collected using the same nationally validated methodology

A method of quality control that uses statistical methods and is an essential component of quality assurance and performance improvement is:

Statistical process control (SPC)

Hill's Criteria - The incidence of disease should be higher in those who are exposed to the factor under consideration than in those who are not exposed; that is, the stronger the association between an exposure and a disease, the more likely the exposure is to be causal. For example, lung cancer is common in those who smoke.

Strength of association

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 to stimulate public health action?

Surveillance

Hill's Criteria - Exposure to the hypothesized causal factor must precede the onset of disease

Temporality

An IP is reading a journal article that states that the data the authors collected are normally distributed. What does this mean?

The mean, median, and mode of the data are equal

Specificity of a test for infection or disease is calculated as:

The number of TRUE NEGATIVES divided by TOTAL # PERSONS WITHOUT DISEASE x100

What is true when the prevalence of disease is very low?

The positive predictive value of a diagnostic test is lowered

Odds Ratio (AKA Relative odds, Cross-product ratio)

The probability of having a particular risk factor if a condition or disease is present DIVIDED BY The probability of having the risk factor if the disease or condition is not present 2x2 table - ad / bc

The p value in statistical test results indicates:

The probability of having committed a Type I error

What is true about Coccidioidomycosis?

Up to 50% of people in endemic areas have been exposed to Coccidioides spores

Incidence Density Rate

When the incidence rate denominator (population) is the sum of the person-time of the at-risk population

The noroviruses are notable because they

are the most common cause of epidemic gastroenteritis worldwide

The standard deviation indicates:

how small the variability is (i.e., the spread) among observations. If the variability is small, all the values are close to the mean. If it is large, the values are not close to the mean.

PPV and NPV are disease prevalence dependent. Generally a higher prevalence will:

increase the PPV and decrease the NPV.

Positive numbers indicate _____kurtosis

lepto (peaked)

Chi-square tests are used for _______________ samples

medium to large

A value of 0 indicates ____kurtosis

meso (normal bell)

A type I error occurs when

one rejects the null hypothesis when it is true (also called a false-positive result)

Negative numbers indicate ____kurtosis

platy (flat)

The estimated probability of rejecting the null hypothesis of a study question when that hypothesis is true is:

the P value or calculated probability

The main advantage of nonparametric methods is that:

the assumptions of normality are not required.

If chance is a likely explanation for the difference between a sample statistic and the corresponding null hypothesis population value, then:

the difference is not statistically significant

The positive predictive value (PPV) describes:

the probability of having the disease given a positive screening test result in the screened population

The negative predictive value (NPV) describes:

the probability of not having the disease given a negative screening test result in the screened population.

The Fisher's exact test is used in place of Chi-square tests when:

the sample size is <20 or any cell in the table is <5

Chi-square tests can be used to test the association between:

two classifications of a set of counts or frequencies (discrete data)