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Obesity is highly correlated with the development of chronic diseases and has become a critical public health issue that must be countered by aggressive action. This study determined whether data from Google Trends could provide insight into trends in obesity-related search behaviors in Taiwan.
Using Google Trends, we examined how changes in economic conditions—using business cycle indicators as a proxy—were associated with people’s internet search behaviors related to obesity awareness, health behaviors, and fast food restaurants.
Monthly business cycle indicators were obtained from the Taiwan National Development Council. Weekly Taiwan Stock Exchange (TWSE) weighted index data were accessed and downloaded from Yahoo Finance. The weekly relative search volumes (RSV) of obesity-related terms were downloaded from Google Trends. RSVs of obesity-related terms and the TWSE from January 2007 to December 2011 (60 months) were analyzed using correlation analysis.
During an economic recession, the RSV of obesity awareness and health behaviors declined (
Macroeconomic conditions can have an impact on people’s health-related internet searches.
Obesity is highly correlated with the development of several chronic diseases, including cardiovascular disease and type 2 diabetes [
Studies have found that the prevalence of obesity shifts toward lower socioeconomic status groups as a country’s gross national product increases [
Several studies have also indicated a potential association between macroeconomic conditions and obesity-related health behavior. For example, one study used a convenience sample from a metropolitan city in the US Midwest and discovered that an economic downturn may increase rates of obesity by forcing families to cut their food expenditure [
The most recent global recession (Great Recession, 2008-2009) was the most severe, as measured by duration, since the Great Depression of the 1930s [
Individuals today often use the internet and various search engines, such as Google and Yahoo, to obtain information to support their decisions [
Google Trends also has predictive capacity for monitoring the epidemic curves of food-borne illnesses, such as peanut butter-associated outbreaks of
The purpose of this study was not to contest or generate additional theories to support the contentious link between macroeconomic conditions and obesity-related health behaviors, but rather it was to understand how an economic downturn might affect obesity-related internet search behavior. Thus, by using Google Trends we investigated how changes in economic conditions—using business cycle indicators as a proxy—affected people’s internet search behaviors, including searches related to obesity awareness, obesity-related health behavior, and fast food restaurants.
The 2008-2009 economic recession was the most severe since the Great Depression of the 1930s; therefore, it provides an excellent opportunity to study how the business cycle affects internet search behaviors for health-related issues [
In this study, the recession period was defined as the time when the business cycle indicator dropped below the stable stage, climbed to the transitional stage (above 23) from April 2008 through September 2009, and then returned to growth until December 2011 (see
Google Trends analyzes all search queries of a specific term to quantify interest in topics at the population level, thus serving as an increasingly useful research tool. Relative search volume (RSV) is the proportion of searches for a given term out of all searches for a given geographic location and time period, which is then normalized to a 0-100 scale [
Google Trends only reports results above a certain threshold. When Google Trends cannot report the search volume for a term, the message displayed is, “Not enough search volume to show graphs.” Thirty-four search terms had insufficient search volume. Weekly data on the remaining 15 search terms from January 2007 to December 2011 (60 months) were accessed and downloaded from Google Trends on June 28, 2016.
Taiwan business cycle indicators.
Time series for the monthly business cycle indicator and Taiwan Stock Exchange Weighted Index (TWSE) between January 2006 and December 2011.
List of obesity-related search terms.
Category | Search terms |
Awareness terms | Obesity; metabolic syndrome; endocrinology; triglycerides; body fat percentage; body mass index |
Health behavior terms | Healthy diet; aerobics; effective diet; meal replacement; on a diet; fitness |
Fast food restaurant terms | McDonald’s; KFC; pizza |
As stock market volatility is a predictor for macroeconomic volatility [
Pearson correlation coefficient analysis is widely used in Google Trends research [
Nowcasting, also known as contemporaneous forecasting, is used to describe the extent of a current association. During the prefinancial crisis period, the RSV of health behaviors was positively associated with the TWSE (
Second, during the period of the financial crisis, all RSVs of the three categories were correlated with the TWSE. The RSV of obesity awareness and health behavior declined while the TWSE declined (
Third, the RSV of obesity awareness and health behavior correlated with the TWSE after the financial crisis, but the correlation coefficient changed from a positive to a negative direction (
In addition to the nowcasting effect, the forecasting effect can be used to determine the TWSE’s lead pattern over the search trends. As aforementioned, for example, a 1-month lead TWSE represented the correlation between the TWSE in January 2009 and obesity-related searches in February 2009. All figures are reported in
Relative search volumes (RSVs) by categories.
Time period | Search volume indexes (RSVs) | ||
Awareness (% change) | Behavior (% change) | Fast food (% change) | |
Reference (before prefinancial crisis; 2006/10/1-2007/9/29) | 34 | 23 | 23 |
Prefinancial crisis (2007/9/30-2008/3/29) | 32 (–6) | 23 (0) | 27 (16) |
Financial crisis (2008/3/30-2009/8/29) | 30 (–6) | 20 (–12) | 34 (27) |
Postfinancial crisis (2009/8/30-2011/5/28) | 29 (–3) | 19 (–5) | 38 (12) |
Time trends for queries of the three categories around the Great Recession.
Pearson cross-correlation analysis of search terms and Taiwan Stock Exchange (TWSE), 2007-2011.
Attribute and time period | TWSE preceded search terms by time ( |
|||
No lag | 1 month | 3 months | ||
Prefinancial crisis (2007/9/30-2008/3/29) | .277 (.170) | .086 (.677) | .087 (.674) | |
Financial crisis (2008/3/30-2009/8/29) | .441 (<.001) | .453 (<.001) | .318 (.006) | |
Postfinancial crisis (2009/8/30-2011/5/28) | –.554 (<.001) | –.595 (<.001) | –.354 (.001) | |
Prefinancial crisis (2007/9/30-2008/3/29) | .504 (.009) | .421 (.032) | .344 (.086) | |
Financial crisis (2008/3/30-2009/8/29) | .593 (<.001) | .646 (<.001) | .388 (.001) | |
Postfinancial crisis (2009/8/30-2011/5/28) | –.548 (<.001) | –.405 (<.001) | –.298 (.004) | |
Prefinancial crisis (2007/9/30-2008/3/29) | –.529 (.006) | –.640 (<.001) | –.028 (.893) | |
Financial crisis (2008/3/30-2009/8/29) | –.437 (<.001) | –.513 (<.001) | –.530 (<.001) | |
Postfinancial crisis (2009/8/30-2011/5/28) | .049 (.646) | .095 (.372) | .181 (.086) |
First, during the prefinancial crisis period, a 1-month lead TWSE was statistically associated with the RSVs of health behaviors and fast food (
For searches using obesity awareness and health behavior terms, the TWSE showed a 3-month predictive power with positive association, suggesting that the stock market collapse was followed 3 months later by a decline in interest for obesity awareness and health behaviors. These results imply that people were more likely to disregard obesity-related health issues when the business cycle fell into recession. Furthermore, the TWSE was negatively related to the RSV of fast food restaurants (
Third, after the financial crisis period, although a business cycle and stock market turnaround took place, searches for obesity awareness and health behavior did not follow the same trend. In contrast, both categories of search terms demonstrated a negative correlation with TWSE, suggesting that obesity-related health issues may have been lower than before the economic downturn due to the economic recovery, which lead to job opportunity increases (lower unemployment).
Finally, fast food consumption has been assumed to be a potential risk factor for being overweight and obese, due to the high energy densities and high glycemic loads associated with such foods [
Our findings support this relationship by demonstrating the negative correlation between TWSE and fast food searches during the financial crisis period (
The consumer price index (CPI) tracks monthly data on changes in the prices paid by consumers for a specific or representative basket of goods and services [
S&P 500 and McDonald’s Corp. (MCD:NYSE) share performance between 2007 and 2010.
Consumer price index and unemployment trends, 2008-2016.
Pearson cross-correlation analysis of the correlation between consumer price index and unemployment for meat, fruit, and cigarettes and betel nuts (2008-2016).
Variable | Unemployment | Meat | Fruit | Cigarette and betel nuts |
Unemployment | 1.00 | |||
Meat ( |
.209 (0.32) | 1.00 | ||
Fruit ( |
–.421 (<.001) | .003 (.974) | 1.00 | |
Cigarettes and betel nuts ( |
.220 (.024) | .599 (<.001) | –.094 (.339) | 1.00 |
This study contributes to an understanding of how business cycles are related to online searches for obesity-related awareness, health behavior, and fast food restaurants. The results revealed a positive association between the TWSE, obesity-related awareness, and health behavior searches during the prefinancial and financial crisis periods, suggesting that economic hardship may be the underlying force affecting individual obesity-related internet searches. Previous studies have indicated that individuals may engage in less physical activity or cease membership of health and sports clubs during periods of economic downturn [
The results suggested that the performance of the TWSE moderately correlated with these search trends, demonstrating the possibility that monitoring the TWSE could plausibly predict future obesity-related searches on the internet. Additionally, the results also suggested that the TWSE demonstrated a 3-month leading effect; however, the 1-month leading effect was much stronger during the prefinancial crisis and financial crisis periods.
Finally, our results suggested that the TWSE could also play a role in monitoring changes in obesity-related aggregated individual search behaviors at population scale. If so, one of the primary indicators of economic prosperity not only represents the nation’s economy but is also a leading indicator of population health. This study provides a new methodological lens for improving the monitoring of obesity. This method can help governments recognize that recessions may result in an increase in obesity-related problems. While addressing the issues of a stalling job market and high unemployment, governments should also look to provide resources for dealing with obesity.
Due to the Google Trends algorithm, several limitations of this study should be noted. First, there was difficulty in identifying search trends that were generated by true cases. In particular, Google Trends tends to be influenced by media exposure of specific diseases (eg, drug advertisements), which drives more nonrelated individuals to search for terms and thus increases the search volume [
In conclusion, internet search data can be a potentially useful tool for health policy makers to identify obesity-related issues and possible obesity problems within the population. Google Trends serves as an easily accessible and real-time surveillance tool. Despite its limitations, this study highlighted Google Trends as a useful tool for establishing a plausible relationship between obesity-related search terms and macroeconomic events.
List of Chinese obesity-related search terms and their English equivalents.
autoregressive integrated moving average
consumer price index
health belief model
relative search volumes
Taiwan Stock Exchange
None declared.