Lecture 3: Analyzing, Communicating & Disseminating Surveillance Data Flashcards
Steps to analyze surveillance data
- know idiosyncrasies of the surveillance data set
- proceed from simplest to most complex
- recognize limitations of the data
- report findings to stakeholders and those who run the surveillance system
Types of analysis of surveillance systems
- descriptive analysis
- inferential analysis
- aberration detection
- demographic data analysis
Descriptive analysis
Looks at…
- Person (graph showing lyme disease cases in females vs males from age 5 to 80)
- Place (graph showing cluster of lyme disease in northeast and how that has been spreading within the northeast in the last 10 years)
- Time (shows lyme disease case incidence over time in the US)
- Measures (frequency, rates, central tendency, proportions)
Inferential analysis
- trend analysis
- survival analysis
- spatial and temporal aberration detection
- cross-sectional data
- analysis of data from complex surveys
Trend analysis
- Asks whether things are changing (getting better or worse) over time
- Two types of trend analyses
1) Monotonic trends: change at a constant rate over time
2) Non-monotonic trends: change in trends is inconsistent over time
Annual Percentage Change (APC or cAPC)
assumes a constant rate of change holds for the entire period
Segmented Annual Percent change (sAPC)
segmented analysis of changes in trend which:
- assumes the change in rates is constant over each time partition defined by the transition points
- assumes the change in rates varies among different time partitions
Annual percentage change (AAPC)
- summary measure of the trend over a pre-specified fixed interval which takes into account the trend tradition
- has advantage over the APC because it does not assume constant trend pattern that may not hold
- when trend is constant over the entire time interval, AAPC is reduced to both cAPC and sAPC
Calculation in monotonic trend analysis
-See lecture 3 slide 16
-relative difference of the proportions in each group
-AAPC= {Exp (Sigma wb)-1}100
w is length of each segment in years and b is slope for each segment in the desired range of years
-CI AAPC = {Exp log((AAPC/100)+1)+/_ 1.96(SQ Root(Sigma wsd)-1}*100
Non-monotonic trend analysis
- Regression analysis (difficult to explain)
- Jointpoint analysis (software models the number of times and when the trend changes)
Survival Analysis
- Asks whether there is a difference in survival rates between the groups being compared
- Kaplan Meier (a non-parametric method used to investigate the unadjusted survival times of a group without influence of other covariates in the model. Used when cox proportional hazards assumption is violated)
- Cox proportional hazards (a semi-parametric method used when there are many explanatory variables you must adjust and when some of these are continuous; assumes that hazard functions of different individuals remain proportional and constant over time)
Spatial aberration detection
- Asks whether there are 1) clusters of disease, 2) patterns in local rates observed in small areas, etc.
- 1) needs location data to determine clusters (calculate Tango’s index or use SaTScan)
- 2) needs data such as area case counts and population at risk, small-area estimation
- method to detect clusters (bayesian theory)
Spatial aberration detection: Tango’s index
measure of geographical closeness between regions (ranges from 0 to 1)
Spatial aberration detection: SaTScan
detects spatial or space-time clusters, tests if a disease is randomly distributed over space, time or over space and time
Temporal Aberrations
-Asks when do we have sufficient cases to determine that there is an increase in cases that warrants a PH intervention
-requires historical frequency of disease data
uses graphs of current and past experience, scan statistics, and time-series methods
Temporal Aberrations: Graphs of current and past experience
Sum data from current four week period, calculate historical mean and SD (sum data from previous, same and subsequent 4-week periods from preceding 5 years and divide by total number of weeks.
Temporal Aberrations: Time series methods
- methods used are: moving average and autoregressive integrated moving averages
- accounts for period to period correlations, seasonality and long term secular trends
- only disadvantage is that many years of data is needed
Demographic data analysis
- standardization (ex: age adjustment)
- life tables probabilities (cohort, period)
- population estimation and projections
- age, period and cohort (APC) effects (seen diagonally)
- disaggregation of proximate determinants of disease
Visual Display of Data
- Tables (arrange data in rows and columns)
- graphs (visual display of quant data using system of coordinates)
- charts (displays statistical info and useful for comparing magnitude of events in categories of a variable)
- maps
- interactive displays of data
Commonly used dissemination media
- social media
- email updates (cdc, WHO)
- news media
- conferences
- publications (MMWR)
Two Communication models
- Simple communication model
- Integrated communication model
Definitions: Messages
info that is encoded and may take the form of symbols, words, or pictures
Definitions: Source
institutions or individuals who send the message
Definitions: channels
mechanism by which the message is transmitted
Definitions: audience
one or several persons who receive the message
Simple communication model
Source/channel–>message–> audience/receiver
Integrated communication model
- Incorporates both surveillance and program loops with data collection, data analysis, data interpretation and information dissemination in the former. program planning, program implementation, program evaluation and info dissemination in the latter.
- Both surveillance and program loops converge on information dissemination to give feedback
Communication Framework
- assess quality of the surveillance info (requires understanding of epi, surveillance and the surveillance system)
- define the purpose of communicating the info
- define the audience (TARGET: health care providers, individuals or policy makers. CHALLENGES: demography of the target audience, culture, STEM literacy)
- develop the message (condense info to simple words or images and pre-test on target audience)
- select the channel (interpersonal, written material and audio-visual, mass media, electronic and other new media)
- market the info (not selling, but objective is to gain attention and interest)
- implement the communication plan
- evaluate the process and outcome
define the purpose of communicating the info in order to..
- detect and control outbreaks
- determine the etiology and natural history of disease
- evaluate control measures
- detect changes in disease agents
- detect changes in health practices
- facilitate planning of health policies
- informing to increase knowledge
- persuading to provide info and change audience attitude, beliefs, intention or behaviors
Develop the message: what is SOCO?
Single overriding communication objective must be created in developing the message
What are the 4 P’s of marketing?
- product, price, place, and promotional strategy
- identification, selection and development of a product
- determination of its price
- selection of a distribution channel to reach the customer’s place
- development and implementation of promotional strategy
Some Marketing Strategies
- transmission systems (active and passive)
- formatting
- packaging
- timing
Crisis and Emergency Risk communication
STARCC–>
- Simple
- Timely
- Accurate
- Relevant
- Credible
- Consistent
