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. 2012 Jul 19;7(7):e40014. doi: 10.1371/journal.pone.0040014

Figure 2. Query log volumes and trading volumes: cross correlation analysis (ticker: “NVDA”).

Figure 2

(up) Time evolution of normalized query-logs volumes for the ticker “NVDA” compared with the trading-volume of the “NVIDIA Corporation”. The data for both query-logs (blue) and trading volume (red) are aggregated on a daily basis. (bottom) The plot of the sample cross correlation function Inline graphic as defined in Eq. (1) Inline graphic absolute values of the time lag Inline graphic (positive values of Inline graphic correspond to solid lines while negative values of the time lag correspond to the broken lines). The correlation coefficients at positive time lags are always larger than the corresponding at negative ones, this suggests that today’s query volumes anticipate and affect the trading activity of the following days (typically one or two days at most).