Table 4. Summary of model characteristics.

Model	Training period1	Google Trends data2	Keyword selection3	Model Name4
1	52 weeks	Raw data	Continuous	52RC
2	52 weeks	Wavelet transformed	Continuous	52WC
3	104 weeks	Raw data	Continuous	104RC
4	104 weeks	Wavelet transformed	Continuous	104WC
5	156 weeks	Raw data	Continuous	156RC
6	156 weeks	Wavelet transformed	Continuous	156WC
7	52 weeks	Raw data	Set	52RS
8	52 weeks	Wavelet transformed	Set	52WS
9	104 weeks	Raw data	Set	104RS
10	104 weeks	Wavelet transformed	Set	104WS
11	156 weeks	Raw data	Set	156RS
12	156 weeks	Wavelet transformed	Set	156WS

¹The training period denotes how many weeks data are available to the model for fitting, keyword selection and wavelet construction. This period was also used to determine the best lag for keywords used in these models (but was restricted to the 2009–2011 data).

²Indicates the search metrics data available for the model.

³In producing forecasts for holdout data (2012–2013), continuous models are able to reselect keywords at each time point using the previous 52, 104 or 156 weeks data; set models use a selection of keywords determined using only the 2009–2011 data.

⁴Models are named using a combination of the number of weeks data visible to them (52/104/156), format of search metric data (raw/wavelet transformed; R/W) and the method of keyword selection (continuous/set; C/S).