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J Med Internet Res. 2014 Dec 16;16(12):e289.
Cumulative Query Method for Influenza Surveillance Using Search Engine Data.
Seo DW1, Jo MW, Sohn CH, Shin SY, Lee J, Yu M, Kim WY, Lim KS, Lee SI.
Author information
Abstract
BACKGROUND:
Internet search queries have become an important data source in syndromic surveillance system. However, there is currently no syndromic surveillance system using Internet search query data in South Korea.
OBJECTIVES:
The objective of this study was to examine correlations between our cumulative query method and national influenza surveillance data.
METHODS:
Our study was based on the local search engine, Daum (approximately 25% market share), and influenza-like illness (ILI) data from the Korea Centers for Disease Control and Prevention. A quota sampling survey was conducted with 200 participants to obtain popular queries. We divided the study period into two sets: Set 1 (the 2009/10 epidemiological year for development set 1 and 2010/11 for validation set 1) and Set 2 (2010/11 for development Set 2 and 2011/12 for validation Set 2). Pearson's correlation coefficients were calculated between the Daum data and the ILI data for the development set. We selected the combined queries for which the correlation coefficients were .7 or higher and listed them in descending order. Then, we created a cumulative query method n representing the number of cumulative combined queries in descending order of the correlation coefficient.
RESULTS:
In validation set 1, 13 cumulative query methods were applied, and 8 had higher correlation coefficients (min=.916, max=.943) than that of the highest single combined query. Further, 11 of 13 cumulative query methods had an r value of ≥.7, but 4 of 13 combined queries had an r value of ≥.7. In validation set 2, 8 of 15 cumulative query methods showed higher correlation coefficients (min=.975, max=.987) than that of the highest single combined query. All 15 cumulative query methods had an r value of ≥.7, but 6 of 15 combined queries had an r value of ≥.7.
CONCLUSIONS:
Cumulative query method showed relatively higher correlation with national influenza surveillance data than combined queries in the development and validation set.
KEYWORDS:
Google Flu Trends; Internet search; influenza; influenza-like illness; query; syndromic surveillance system
PMID: 25517353 [PubMed - as supplied by publisher] Free full text
Cumulative Query Method for Influenza Surveillance Using Search Engine Data.
Seo DW1, Jo MW, Sohn CH, Shin SY, Lee J, Yu M, Kim WY, Lim KS, Lee SI.
Author information
Abstract
BACKGROUND:
Internet search queries have become an important data source in syndromic surveillance system. However, there is currently no syndromic surveillance system using Internet search query data in South Korea.
OBJECTIVES:
The objective of this study was to examine correlations between our cumulative query method and national influenza surveillance data.
METHODS:
Our study was based on the local search engine, Daum (approximately 25% market share), and influenza-like illness (ILI) data from the Korea Centers for Disease Control and Prevention. A quota sampling survey was conducted with 200 participants to obtain popular queries. We divided the study period into two sets: Set 1 (the 2009/10 epidemiological year for development set 1 and 2010/11 for validation set 1) and Set 2 (2010/11 for development Set 2 and 2011/12 for validation Set 2). Pearson's correlation coefficients were calculated between the Daum data and the ILI data for the development set. We selected the combined queries for which the correlation coefficients were .7 or higher and listed them in descending order. Then, we created a cumulative query method n representing the number of cumulative combined queries in descending order of the correlation coefficient.
RESULTS:
In validation set 1, 13 cumulative query methods were applied, and 8 had higher correlation coefficients (min=.916, max=.943) than that of the highest single combined query. Further, 11 of 13 cumulative query methods had an r value of ≥.7, but 4 of 13 combined queries had an r value of ≥.7. In validation set 2, 8 of 15 cumulative query methods showed higher correlation coefficients (min=.975, max=.987) than that of the highest single combined query. All 15 cumulative query methods had an r value of ≥.7, but 6 of 15 combined queries had an r value of ≥.7.
CONCLUSIONS:
Cumulative query method showed relatively higher correlation with national influenza surveillance data than combined queries in the development and validation set.
KEYWORDS:
Google Flu Trends; Internet search; influenza; influenza-like illness; query; syndromic surveillance system
PMID: 25517353 [PubMed - as supplied by publisher] Free full text