Real-time outbreak and disease surveillance system (RODS) is a

syndromic surveillance Public health surveillance (also epidemiological surveillance, clinical surveillance or syndromic surveillance) is, according to the World Health Organization (WHO), "the continuous, systematic collection, analysis and interpretation of health-rela ...

system developed by the

University of Pittsburgh The University of Pittsburgh (Pitt) is a Commonwealth System of Higher Education, state-related research university in Pittsburgh, Pennsylvania, United States. The university is composed of seventeen undergraduate and graduate schools and colle ...

, Department of Biomedical

Informatics Informatics is the study of computational systems. According to the Association for Computing Machinery, ACM Europe Council and Informatics Europe, informatics is synonymous with computer science and computing as a profession, in which the centra ...

. It is "prototype developed at the University of Pittsburgh where real-time clinical data from emergency departments within a geographic region can be integrated to provide an instantaneous picture of symptom patterns and early detection of

epidemic An epidemic (from Greek ἐπί ''epi'' "upon or above" and δῆμος ''demos'' "people") is the rapid spread of disease to a large number of hosts in a given population within a short period of time. For example, in meningococcal infection ...

events."''Public Health-Related Activities'' at th
US HHS government website
Accessed December 2, 2010. RODS uses a combination of various monitoring tools. # The first tool is a

moving average In statistics, a moving average (rolling average or running average or moving mean or rolling mean) is a calculation to analyze data points by creating a series of averages of different selections of the full data set. Variations include: #Simpl ...

with a 120-day sliding phase-I-window. # The second tool is a nonstandard combination of

CUSUM In statistical process control, statistical quality control, the CUSUM (or cumulative sum control chart) is a sequential analysis technique developed by E. S. Page of the University of Cambridge. It is typically used for monitoring change detecti ...

and EWMA, where an EWMA is used to predict next-day counts, and a CuSum monitors the residuals from these predictions. # The third monitoring tool in RODS is a

recursive least squares Recursive least squares (RLS) is an adaptive filter algorithm that recursively finds the coefficients that minimize a Weighted least squares, weighted linear least squares Loss function, cost function relating to the input signals. This approach is ...

(RLS) algorithm, which fits an

autoregressive model In statistics, econometrics, and signal processing, an autoregressive (AR) model is a representation of a type of random process; as such, it can be used to describe certain time-varying processes in nature, economics, behavior, etc. The autoregre ...

to the counts and updates estimates continuously by minimizing

prediction error In statistics the mean squared prediction error (MSPE), also known as mean squared error of the predictions, of a smoothing, curve fitting, or regression procedure is the expected value of the squared prediction errors (PE), the square differenc ...

. A Shewhart I-chart is then applied to the residuals, using a threshold of 4

standard deviations In statistics, the standard deviation is a measure of the amount of variation of the values of a variable about its mean. A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the ...

. # The fourth tool in RODS implements a

wavelet A wavelet is a wave-like oscillation with an amplitude that begins at zero, increases or decreases, and then returns to zero one or more times. Wavelets are termed a "brief oscillation". A taxonomy of wavelets has been established, based on the n ...

approach, which decomposes the time series using

Haar wavelet In mathematics, the Haar wavelet is a sequence of rescaled "square-shaped" functions which together form a wavelet family or basis. Wavelet analysis is similar to Fourier analysis in that it allows a target function over an interval to be repr ...

s, and uses the lowest resolution to remove long-term trends from the raw series. The residuals are then monitored using an ordinary Shewhart I-chart with a threshold of 4 standard deviations.

References

Public health Epidemics Medical statistics Epidemiological study projects Infection-control measures {{epidemic-stub