摘要：The modi ed autoregressive (mAR) index has been proposed as adescription of the clustering of shots of similar duration in a motion picture.In this paper we derive robust estimates of the mAR index for high grossing lms at the US box oce using a rank-based autocorrelation function resis-tant to the inuence of outliers and compare this to estimates obtained usingthe classical, moment-based autocorrelation function. The results show that(1) The classical mAR index underestimates both the level of shot clusteringin a lm and the variation in style among the lms in the sample; (2) thereis a decline in shot clustering from 1935 to the 1950s followed by an increasefrom the 1960s to the 1980s and a levelling o thereafter rather than themonotonic trend indicated by the classical index, and this is mirrored in thetrend of the median shot lengths and interquartile range; and (3) the rankmAR index identi es di erences between genres overlooked when using theclassical index.
关键词：autocorrelation; lm editing; modi ed autoregressive index; ro-;bust methods
