Tuesday, May 12, 2015

What is Google Trend? And which forecasting methods can be used with Google Trend data?


Google Trends is an online search tool that allows user to see how often particular keywords, subjects or phrases have been searched and asked for over a specific period of time. Just like that, Google trends graphs often show a term that is used over time and where geographically most people are searching for a given term.
Significantly, Google trend enable us to perform advanced keyword analysis, examine seasonal search patterns, discover a new untapped keyword, increase relevant traffic sales and save individual months of time and energy (Lyons, 2010). Particularly, Google trends also provide daily and weekly reports on the volume of queries, which related to various industries and companies. As a matter of fact, have you ever noticed that the search share for coupon increases during the holiday shopping season and the summer vacation season? The query (car tire) would be assigned to category vehicle tires, which is a subcategory of auto parts that is a subcategory of automotive. Nevertheless, research showed that they are not claiming that Google trends data can help in predicting the future but they are claiming that Google trends might help in predicting the present. For instance, the volume of queries on automobile sales during the second week in June may be helpful in predicting the June auto sales report, which is released several weeks later in July. It may also be true that June queries help to predict July sales, but researcher leave that question for future research, as this depends very much on the particular time series in question (Hyunyoung Choi, Predicting the Present with Google Trends, 2011). As a result, researcher found out that queries can be quite useful in leading indicators for subsequent consumer purchases in situations where consumers start planning purchases significantly in advance of their actual purchase decision.

Basically, there are many forecasting methods that can be used with Google trend data but we will point out four potential methods that usually implement from time to time. Firstly, linear regression is one of the widely use method for forecasting method since it could analyze the use of an independent variable to predict a dependent variable. To bear in mind, we can use changes in an independent variable to forecast changes in dependent variable if there is a strong correlation between a dependent variable and an independent variable (theweeklytrade, 2010). Namely, the author gave intensive information of search frequencies as an independent variable, which used housing price and sale volume as an independent variable. The research also had shown that there is a high correlation between search frequencies and housing sales while there is a moderate relationship between search frequencies and housing price. Secondly, talking about Google trends, it has characterized the predictability of a trend series based on its historical performance (Weiss, 2009). According to the research, in order to do so they compared the difference of forecasted trends, which applied at some point in the past, to the trend actual performance. Once the difference between the forecasted trends and the actual trends is smaller than a predefined level, Google represents the trends query as predictable. On the other hand, the article also stated that Google trends provide a time series index of the volume of queries users enter into Google in a given geographic area. The query index is based on query share, which equal to the total query volume for the search term in question within a particular geographic region divided by the total number of queries in that region during the time period being examined (Hyunyoung Choi, Predicting the Present with Google Trends, 2011).
As a matter of fact, Google trend index value or formula = {search queries volume at period (relative value) / Total search volume (highest relative value)} *100
The study had shown that the scale is presented in the range of 0-100, where 100 represent the search peak or the highest frequency and intensity of searching activity for the specific query. Trends Index values for every period are calculated by dividing the relative value by the highest relative value (Hyunyoung Choi, Predicting the Present with Google Trends, 2011).

Table 3 numerical example of Google Trends computation.

1
2
3
4
5
6
7
A number of new search quires (A)
100
200
300
400
500
600
1200
Total volume of search queries (B)
500
700
1000
1400
1900
2500
3700
Relative value (=A/B)
0.20
0.29
0.30
0.29
0.23
0.24
0.32
Google Trends Index value1
62
88
93
88
81
74
100
Source: Compiled by the authors. (Gerard Chmyznikov, 2013)

Thirdly, another model or method would follow the following model, which use for analyzing and forecasting with Google trends data. The author assumed that model predicts and forecast about the sale of a company (Hyunyoung Choi, Predicting the Present with Google Trends, 2011).
+Model 0:
-log(yt) ~ log(yt-1) + log(yt-12) + et
This model predicts the sales of this month using the sales of last month and 12 months ago
+Model 1
-log(yt) ~ log(yt-1) + log(yt-12) + xt(1) + et
This model uses an extra predictor, i.e. Google query index to predict the sales of the present.
-log(yt) = 2.312 + 0.114*log(yt-1) + 0.709*log(yt-12) + 0.006*xt(1)
Sales of present month is positively correlated with the sales of last month, the month 12 months before and the Google query
-log(yt) = 2.007 + 0.105*log(yt-1) + 0.735*log(yt-12)0.005*xt(1)+0.324*I(July 2005)
Remarkably, there was a special promotion week in July 2005, so they have added a dummy variable to control for that observation and re-estimated the model
By the same token, it is essential to use prediction error and mean absolute error along with the model above in order to produce the best result and come out effectively.
-Prediction error: Predicted value – observed value
-Mean absolute error: Average of the absolute values of the prediction errors (Hyunyoung Choi, Predicting the Present with Google Trends, 2011).

Thus, it would come out with graph below:

Last but definitely not least, another forecasting method that could be used with Google trends is R, which would be able to convert the data to a time series with a 52-week frequency (Google Trends reports weekly search data) (Morrison, 2012). It seems fantastically useful. Below are the codes (including all the Google data):

Which result in

Hence, converted the search index time series into a Holt Winters object. The Holt Winters function comes as standard with R, so nothing to do here. But this is just a proof-of-concept run:

Which produced a nice looking fit, based on the trend and 52 individual coefficients:


Forecast package, and run the forecast. Holt Winters function for the next year.


Which, in turn, gives this:
Forecast, the orange area gives the 80% confidence interval and the yellow the 95% confidence interval (Morrison, 2012).

In conclusion, Google trends give user with the consumption of choices, check competitors especially would be pivotal for blogger or website which can help drive more traffic to their own site. Undoubtedly, Google trends is not only useful for business sector or marketer but also in many other aspect of life since people can use it as a path of better decision making and self awareness for their own living.





Bibliography

Weiss, D. T. (2009, September 07). On Google’s new forecasting capabilities and their importance to Market Research. Retrieved from trendsspotting.com: http://www.trendsspotting.com/blog/?p=1536
Morrison, M. (2012, November 26). Forecasting Google search volume using R. Retrieved from blog.magicbeanlab.com: http://blog.magicbeanlab.com/data-viz/forecasting-search-volume/
Lyons, K. (2010, April 21). Case Study: Using Google Trends to Discover New PPC. Retrieved from ppchero.com: http://www.ppchero.com/case-study-using-google-trends-to-discover-new-ppc-opportunities/
Gerard Chmyznikov, L. G. (2013, November). FORECASTING ECONOMIC ACTIVITY IN THE BALTICS: LET US GOOGLE IT.
Hyunyoung Choi, H. V. (2011, December 18). Predicting the Present with Google Trends.
theweeklytrade. (2010, October 08). Can Google Predict the Future? Retrieved from hotstockmarket.com: http://www.hotstockmarket.com/t/80890/can-google-predict-the-future

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