CIC to review: Stats and Epi Flashcards
Chart used to compare values across multiple groups
Bar
Types of data used for bar graph
1 Q
1 C
Chart used to examine distribution of quantitative variable by splitting it into multiple groups
Histogram
Data types for histogram
2Q (one displayed as groups)
Bars represent mutually exclusive groups
Chart used to show changes over time
Line chart
Types of data for line chart
1Q, 1C
Charts used to show how each category contributes to the whole
Pareto
Pie
Types of data for pareto chart
1 Q, 1 C
Types of data for a pie chart
1Q, q C
Chart used to look for correlation between variables
Scatterplot
Data types of scatterplot
2Q
Attributable proportion
RR-1 / RR
Measure of extent to which the distributions of possible results under the research hypothesis and null hypothesis do not overlap
Effect size
subset of sample statistics used to estimate a point characteristic of the population (eg it’s central tendency) rather than it’s dispersion (range, variance, etc)
Point estimate
way of assessing how much independent information is available from you data to estimate the parameter or determine the shape of the distribution
degrees of freedom
Using false positive- what happens if p <= alpha?
the risk of a false positive is acceptable, we reject the null hypothesis and conclude a statistically significant difference exists
Type 1 error
alpha- false positive
Type 2 error
beta- false negative
parametric tests used to determine whether two or more groups differ from each other based on the variability of values within each group versus the variability of values bewtween the groups
ANOVA
A nonparametric test used to evaluate how close the observed counts are for a single variable to those expected if the data fit a specific distribution
Chi square goodness of fit test
A nonparametric test used to determine how different the observed counts are from those expected if there is now association between the tested variables
Chi square test of association (AKA pearson’s chi square or chi-square test for independence)
Tests measuring the strength and direction of the relationship between two quantitative variables
Correlation
Parametric correlation
Pearson’s correlation
Nonparametric correlation
Spearmans
Models used to determine whether the linear relationship between 2+ variables is statistically signficiant, to assess the strength and direction of that relationship, and to predict values of the dependent variable for given values of the independent variables
Linear regression
Models used to predict probability of a particular outcome based on the values of one or more independent variables. The outcome possibilities must be dichotomous (ie survived/ died; infection/ no infection)
Logistic regression
nonparametric alternative to independent samples t-test, used to determine whether two groups differ based on ordinal ranks
Mann-Whitney U-Test AKA Mann-whitney wilcoxin test
Nonparametric test used to determine whether two related groups differ based on responses to a dichotomous variable. It is often applicable to pretest/ posttest studies with matched pairs
McNemar test
Parametric test used to determine whether the average values of two groups (or one group and a test value) are different. Versions of the test differ depending on how many groups are being examined and whether or not they are independent of each other
t-test
non-parametric alternative to the paired-samples t-test, used to compare the median value of a group to that of another group
Wilcoxon signed-rank test
What report shows facilities with need for improvement?
TAP- targeted assessment prevention
What is the CAD?
Cumulative attributable difference- # of infections to prevent to meet goals
Elements of effective surveillance program
- Select methodology
- assess and define pops to be studied
- choose events to monitor
- Determine time pd for observation
- ID surveillance criteria (case definitions)
- ID elements to be collected
- Determine methods for data collection and mangement
- Design interpretive surveillance report
- ID recipients of surveillance report
- Develop written surveillance plan
- surveillance program evalulation
What should be considered when selecting an event for surveillance?
- type of hc setting
- pop being studied
- Procedures performed/ services provided
- acuity of care
- risk assessment
- regulatory requirements
- Available resources
- PH needs
- performance improvement initiatives
- organization objectives
Note- usually high risk/ high volume events
Considerations when writing surveillance report
- Define event, population, setting, time period
- case definition criteria
- numbers
- methods
- purpose
- interpretation
- action/ recommendations
Examples of process events
Compliance with IP protocols
- Isolation
- Safe injection
- HH
- env cleaning
Methods to compare surveillance rates
z-test
SIR
Surveillance summary measure used to track performance across groups over time
Standardized infection ratio
Measure used to target prevention by identifying which locations have highest burden of excess infections
CAD- cumulative attributable difference
Risk adjusted measure used to track device utiliztation
SUR- standardized utilization ratio
Summary measure comparing antimicrobial use within and across facilities to guide stewardship effforts
SAAR- standardized antimicrobial administration ratio
Surveillance that uses real time data for early response
Syndromic surveillance
Surveillance that collects data from sample reporting sites
Sentinel surveillance
Ability to detect specified difference?
Power
What impacts the power in a statistical study?
- sample size
- Significance level (alpha)
- true value of parameter being tested (higher effect size, higher power)
Hill’s criteria
Strength of association
Specificity
Temporality
Biological gradient
plausibility
coherence
experiment
analogy
Incidence of disease is higher in those exposed (example lung cancer common in smokers)
Strength of association
Association observed in numerous studies
Consistency
1 factor, 1 disease
Specificity
Exposure to hypothesized causal factor precedes disease onset
Temporality
Dos/ response relationship (longer 1 smokes, more likely to develop lung cancer)
Biological gradient
Association should be in accordance with other facts known about the natural history of the disease
Coherence
Association in question biologically plausible in light of current knowledge
Plausability
Analogous studies available, experiments completed that show association
Experiement
Similar association shown to be causal
Analogy
Frequency polygpn
X axis- values of the variable (ie age of residents at a nursing home)
y-axis- # of observations connected with straight lines
What test is used if chi square would be used but at least 1 cell <5 or sample size <20
Fisher exact test
Artificial/ Spurious association
May be caused by
- errors in study design
- bias
- errors in analysis
- failure to control for confounding factors
Indirect/ noncausal association
Confounding variable
Causal association
1 factor raises the probability of disease
Examples of primary prevention
Wellness and prevention programs
Immunizations
Example secondary prevention
Early dx
Tertiary prevention
Improve quality of life
Recovered, but still carry the organism
Convalescent carriers
What type of graph is an epi curve and example of?
Histogram
3 D’s of epidemiology
Distribution
Determinants
Deterrents
At what point in disease do primary, secondary, and tertiary prevention happen?
- primary- before disease
- Secondary- pre-clinical, asymptomatic disease
- Tertiary- clinical disease
Who should receive communications about outbreaks
- clinicians working in affected area, get input from them regularly
- patients (consult with admin, ethics, and risk management)
- Update admin, risk management, pt safety, and PR regularly
- findings- broader scientific community
What does an epi-curve answer
Source of infection?
Length of incubation
Case #s increasing/ decreasing
Epi-curve where all cases have the same origin
common source
Epi-curve for person to person spread
Propogated
What is the importance of surveillance in outbreaks?
Early ID
effective control
prevention of secondary cases
resource allocation
Resistance mechanisms never or very rarely ID’d in U.S., pan-resistant organisms with the potential for wide spread in a region
Tier 1
Mechanisms and organisms not regularly found in regiond
Tier 2
Mechanisms and organisms regularly found in a region, but not endemic
Tier 3
what are measure that should always be taken for Tier 1 and 2 organisms
- review patient’s hc exposures prior to and after the positive culture
- Screening hc roommates
- Prospective lab surveillance
- Retrospectice lab surveillance
- prompt notification of hcp and patient and implementation of appropriate TBP
- Clear communication of patient status with transferring facilities
- ICAR
Steps to OB investigation
- confirm presence of OB
- ID inv team
- Verify dx
- Establish preliminary case def
- alert admin and stakeholders
- Detailed lit review
- Method- case finding
- line list and epi curve
- observe/ review pt care activities
10.. environmental sampling? (driven by line list) - implement controls
Follow up steps to an outbreak investigation
- refine the case definition
- case finding and surveillance
- review regulatory controls
- maintain surveillance
- analytical study?
Describe the different types of data
- Categorical
- Nominal
- ordinal - Quantitative
- discrete
- continuous
Proportion
Numerator is a subset of the denominator
What can rates be used for?
-Track trends over time
- assess impact of interventions
- ID emerging patterns
- make strategy adjustments
Relative risk
incidence of outcome in exposed group/ incidence of outcome in unexposed group
Type of studies that you can use relative risk for
Cohort
Attributable proportion
RR-1/RR
Odds ratio
Odds of exposure in group with outcome/ odds of exposure in group without the outcome
Range of values where the population parameter is likely to be
Confidence interval
What test must be used for discrete/ categorical data?
Chi square test
Comparing means in 3+ groups
ANOVA
Comparing means between 2 groups
t-tests
Reasons a hospital may not be able to use SIR
procedure uncommon or hospital small
Method of inquiry that seeks to develop a new theory from group up based on findings
Inductive approach
Testing existing theory from top down
Deductive approach
Qualitative methods that includes complex account of an individual’s experience in context of their social or cultural env
Narrative
Qualitative method that strives to remove individuality and discover essence of phenomenon
Phenomenology
Qualitative method used to generate new theories, explanations, or concepts about a process or series of actions
Grounded theory
Qualitative method in which the goal is to understand lives of individuals meaning of human behavior, linked to culture experiences
Ehtnography
Goal of qualitative studies
- lead to generation of hypotheses
Ability of another researcher to follow decision trail of investigator (documentation of methods, interview script, etc)
Reliability
Using multiple sources to answer the same question
Triangulation
Making investigation conclusions useful to others
Transferability
Sampling methods that selects the most relevant individual for the questions based on the study aim
Purposive sampling
How long do you continue qualitative study?
Sample until questions answered/ no new information gained
What are resources required for qualitative studies?
- time
- connection to the right people
- transcription service, audio/ video recorder/ ect.
Who determines what information can be shared with participants about the qualitative study?
IRB
How to analyze qualitative data
1) manage and organize data
2) familiarize yourself with data
3) Interpret key themes in context of the question
4) develop manuscript or diagram/ matrix
Strengths of qualitative studies
- participants view represented
- development of theory or hypothesis
- discover new insights/ phenomena
Limitations of qualitative studies
- limited generalizability
- time consuming
- investigator bias
- unlikely to be published
Type of study: description of SSI among among patients, accentuating the fear, frustration, and insecurity of patients with this experience
Phenomenology
Type of study: exploration of the process of patient prep for colon surgery to enhance the effectiveness of preoperative prevention practices
Grounded theory
Type of study: study of hospital specific cultural influences on hand hygiene and PPE use
Ethnography
Example of descriptive studies
Case report/ case series
Questions that are answered in meta-analysis
What is known?
What still needs to be addressed?
Ability of a test to detect a specified difference (or the probability of rejecting the null hypothesis when it’s false)
Power
What impacts power?
- sample size
- significance level
- the true value of the parameter being tested
The greater the difference between the true value of a parameter and the value specified in the null hypothesis the _______ the power of the test
Greater
Core elements of asp
Leadership
Commitment
Accountability
Drug expertise
Action
Tracking
Reporting
Education
Core component of antibiotic stewardship program that involves dedicating necessary human, financial and information technology resources
Leadership commitment
Core elements of asp that involves appointing a single leader responsible for program outcomes. Experience with successful programs show that a physician leader is effective
Accountability
Core element of ASP that involves appointing a single pharmacist leader responsible for working to improve antibiotic use
Drug expertise
Core elements of ASP that involves implementing at least one recommended action such as systematic evaluation of ongoing treatment need after a set period of initial treatment ( antibiotic time out after 48 hours)
Action
ASP core element that involves monitoring antibiotic prescribing and resistance patterns
Tracking
ASP core element that involves regular reporting information on antibiotic use and resistance to doctors, nurses and relevant staff
Reporting
ASP Court element that involves educating clinicians about resistance and optimal prescribing
Education
How long does UV radiation take to clean a room?
15 to 20 minutes
Precautions for adenovirus
Contact and standard
Precautions or para influenza
Contact and standard
Precautions for enterovirus
Contact for diapered and incontinent and standard
