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"Frontmatter". In: Analysis of Financial Time Series

"Frontmatter". In: Analysis of Financial Time Series

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THE PCD MODEL 2110 10 20 30 40 500 50 100 1500 2 4 6log(duration)1.0 1.5 2.0 2.5 3.0size, in ticks0 20 40 60 80 1000 20 40 60 80 120-1.0 -0.5 0.0 0.5 1.0direction0 5 10 15 20number <strong>of</strong> tradesFigure 5.15. Histograms <strong>of</strong> intraday transactions data for IBM stock on November 21, 1990:(a) log durations between price changes, (b) direction <strong>of</strong> price movement, (c) size <strong>of</strong> pricechange measured in ticks, and (d) number <strong>of</strong> trades without a price change.where standard deviations <strong>of</strong> the coefficients are 0.415, 0.073, 0.384, and 0.073,respectively. The fitted model indicates that there was no dynamic dependence in thetime duration. For the N i variable, we havePr(N i > 0 | t i , F i−1 ) = logit[−0.637 + 1.740 ln(t i )],where standard deviations <strong>of</strong> the estimates are 0.238 and 0.248, respectively. Thus,as expected, the number <strong>of</strong> trades with no price change in the time interval (t i−1 , t i )depends positively on the length <strong>of</strong> the interval. The magnitude <strong>of</strong> N i when it ispositive isN i | (N i > 0,t i , F i−1 ) ∼ 1 + g(λ i ), λ i = exp[0.178 − 0.910 ln(t i)]1 + exp[0.178 − 0.910 ln(t i )] ,where standard deviations <strong>of</strong> the estimates are 0.246 and 0.138, respectively. Thenegative and significant coefficient <strong>of</strong> ln(t i ) means that N i is positively related tothe length <strong>of</strong> the duration t i because a large ln(t i ) implies a small λ i , whichin turn implies higher probabilities for larger N i ; see the geometric distribution inEq. (5.27).

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