Meta data and supporting documentation

We include a description of the data sets in the meta-data as well as sample code and results from a simulated data set. This dataset is not publicly accessible because: EPA cannot release personally identifiable information regarding living individuals, according to the Privacy Act and the Freedom of Information Act (FOIA). This dataset contains information about human research subjects. Because there is potential to identify individual participants and disclose personal information, either alone or in combination with other datasets, individual level data are not appropriate to post for public access. Restricted access may be granted to authorized persons by contacting the party listed. It can be accessed through the following means: The R code is available on line here: https://github.com/warrenjl/SpGPCW. Format: Abstract 
The data used in the application section of the manuscript consist of geocoded birth records from the North Carolina State Center for Health Statistics, 2005-2008. In the simulation study section of the manuscript, we simulate synthetic data that closely match some of the key features of the birth certificate data while maintaining confidentiality of any actual pregnant women.

Availability 
Due to the highly sensitive and identifying information contained in the birth certificate data (including latitude/longitude and address of residence at delivery), we are unable to make the data from the application section publicly available. However, we will make one of the simulated datasets available for any reader interested in applying the method to realistic simulated birth records data. This will also allow the user to become familiar with the required inputs of the model, how the data should be structured, and what type of output is obtained. While we cannot provide the application data here, access to the North Carolina birth records can be requested through the North Carolina State Center for Health Statistics and requires an appropriate data use agreement.

Description 
Permissions: These are simulated data without any identifying information or informative birth-level covariates. We also standardize the pollution exposures on each week by subtracting off the median exposure amount on a given week and dividing by the interquartile range (IQR) (as in the actual application to the true NC birth records data). The dataset that we provide includes weekly average pregnancy exposures that have already been standardized in this way while the medians and IQRs are not given. This further protects identifiability of the spatial locations used in the analysis. 

File format: R workspace file.

Metadata (including data dictionary)
•	y: Vector of binary responses (1: preterm birth, 0: control)
•	x: Matrix of covariates; one row for each simulated individual
•	z: Matrix of standardized pollution exposures
•	n: Number of simulated individuals
•	m: Number of exposure time periods (e.g., weeks of pregnancy)
•	p: Number of columns in the covariate design matrix
•	alpha_true: Vector of “true” critical window locations/magnitudes (i.e., the ground truth that we want to estimate). 

This dataset is associated with the following publication:
Warren, J., W. Kong, T. Luben, and H. Chang. Critical Window Variable Selection: Estimating the Impact of Air Pollution on Very Preterm Birth.   Biostatistics. Oxford University Press, OXFORD,  UK,  1-30, (2019).

Tags: critical-windows, fine-particulate-matter-pm2-5, preterm-birth
Organization: U.S. Environmental Protection Agency