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Nearly 78 years have passed since Paul L. Dysart, Jr. invented the Negative Volume Index and Positive Volume Index indicators. The indicators remain useful to identify primary market trends and reversals. In 1936, Paul L. Dysart, Jr. began accumulating two series of advances and declines distinguished by whether volume was greater or lesser than the prior day’s volume. He called the cumulative series for the days when volume had been greater than the prior day’s volume the Positive Volume Index (PVI), and the series for the days when volume had been lesser the Negative Volume Index (NVI). A native of Iowa, Dysart worked in Chicago’s LaSalle Street during the 1920s. After giving up his Chicago Board of Trade membership, he published an advisory letter geared to short-term trading using advance-decline data. In 1933, he launched the ''Trendway'' weekly stock market letter and published it until 1969 when he died. Dysart also developed the 25-day Plurality Index, the 25-day total of the absolute difference between the number of advancing issues and the number of declining issues, and was a pioneer in using several types of volume of trading studies. Richard Russell, editor of Dow Theory Letters, in his January 7, 1976 letter called Dysart "one of the most brilliant of the pioneer market technicians." ==Dysart’s NVI and PVI== The daily volume of the New York Stock Exchange and the NYSE Composite Index’s advances and declines drove Dysart’s indicators. Dysart believed that “volume is the driving force in the market.” He began studying market breadth numbers in 1931, and was familiar with the work of Leonard P. Ayres and James F. Hughes, who pioneered the tabulation of advances and declines to interpret stock market movements. Dysart calculated NVI as follows: 1) if today’s volume is less than yesterday’s volume, subtract declines from advances, 2) add the difference to the cumulative NVI beginning at zero, and 3) retain the current NVI reading for the days when volume is greater than the prior day’s volume. He calculated PVI in the same manner but for the days when volume was greater than the prior day’s volume. NVI and PVI can be calculated daily or weekly. Initially, Dysart believed that PVI would be the more useful series, but in 1967, he wrote that NVI had “proved to be the most valuable of all the breadth indexes.” He relied most on NVI, naming it AMOMET, the acronym of “A Measure Of Major Economic Trend.” Dysart’s theory, expressed in his 1967 Barron's article, was that “if volume advances and prices move up or down in accordance (volume ), the move is assumed to be a good movement - if it is sustained when the volume subsides.” In other words, after prices have moved up on positive volume days, "if prices stay up when the volume subsides for a number of days, we can say that such a move is 'good'." If the market “holds its own on negative volume days after advancing on positive volume, the market is in a strong position.” He called PVI the “majority” curve. Dysart distinguished between the actions of the “majority” and those of the “minority.” The majority tends to emulate the minority, but its timing is not as sharp as that of the minority. When the majority showed an appetite for stocks, the PVI was usually “into new high ground” as happened in 1961. It is said that the two indicators assume that "smart" money is traded on quiet days (low volume) and that the crowd trades on very active days. Therefore, the negative volume index picks out days when the volume is lower than on the previous day, and the positive index picks out days with a higher volume. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Negative volume index」の詳細全文を読む スポンサード リンク
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