epi-on-the-island time series regression (tsr) 6-10 july 2015 wed 1: dlnms ben armstrong london...
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Use of Satscan to Detect Spatial Clusters in Five Regions of Britain
Epi-on-the-IslandTime Series Regression (TSR)6-10 July 2015
Wed 1: DLNMs Ben ArmstrongLondon School of Hygiene and Tropical Medicine1
The trailer
DLNMs~200 papers 2011-
At least one in vet epi:
Morignat 2015 Env Res
Easy R package!
The algebra terminology:- Recall general model form[In this example, temperature is the variable of interest.]3Distributed lag non-linear models (DLNMs)The shape story (Nonlinear Ms, eg splines)
The lag story (DLMs)
The lag-shape story (DLNMs)
Autocorrelation not very important outside infectious diseases4
The shape story: non-linear options:Cold effectHeat effectThresholds
5Other non-linear options
6Net RR increment (%)over 28 days per degree above 20 (95% CI):
5.0(3.7,6.3)
4.9(3.6,6.2)
4.9(3.7,6.2)
Recall: distributed lag models (DLM)
The lag story:
7The lag-shape story8The lag-shape problem:
Seek combined virtues of:
Smooth temp-mort curves
Smooth effects of lag.
Solution: assume DLMs for each coefficient of a basis variable .e.g.: RR by temperature (NCS) and lag(NCS)
Heat effects:Different slope for each lag
DLNM: simple(r) caseUse a linear threshold modelFit a distributed lag model (DLM) to the heat slope11DLMs taken from econometricsSimple(r) to general DLNM:
Shape flexibility
+
Lag flexibility
=
Total flexibiltyArmstrong 2006Basis variablesExtend this to any set of basis variables (eg splines)Armstrong 2006
Gasparrini 2010
DLNM R code example (London data)# MAKE DLNM BASIS VARIABLEbasis.temp
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