In effect you are asking a question of the validity of one of the underlying lores of technical analysis: that if the price of a stock rose yesterday, it is more likely to rise today. I suggest you read "A Random Walk Down Wall Street" by Burton Malkiel - Chapter 6 on Technical Analysis and the Random Walk Theory. Specifically p140 "Is there Momentum in the Stock Market?" and the following pages answer your question quite well.
In short he says that the persistence of the belief in repetitive patterns in the stock market is due to a statistical illusion which can be demonstrated by tossing a coin. Assume a stock starts at $1 and if the toss is a head, assume that the stock closed 1c higher and if a tale, down by 1c. The chart derived from random coin tossing looks remarkably like a normal stock price chart and even appears to display cycles head-and-shoulder formations, triple tops and bottoms "and other more esoteric chart patterns. Ones of the charts [constructed by the random coin tossing of a student of Malkiel] showed a beautiful upward breakout from an inverted head and shoulders… I showed it to a chartist friend of mine who practically jumped out of his skin "What is this company?" he exclaimed. "We’ve got to buy immediately this pattern is a classic. There’s no question this stock will be up 15 points next week." He didn’t respond kindly to me when I told him that the chart had been produced by flipping a coin."
In the book, Burton dismisses the central proposition of charting very well IMO. In summary, he explains how technical rules have been tested exhaustively by using stock price data on all major exchanges going back as far as the beginning of the twentieth century. The results reveal that past movements in stock prices cannot be used to reliably foretell future movements. The correlation of past price movements with present and future price movements is slightly positive but very close to zero. In any case, slippage eliminates any statistical advantage. Also, technical analysis becomes a self-fulfilling prophecy because traders tend to anticipate technical signals – so in effect cause technical signals and thus destroy any worth in them. Similarly the sporting misconception of, for example ‘streak shooting’ has been statistically discharged. "Psychologists did a detailed study of every shot taken by the Philadelphia 76ers over a full season and a half and found no evidence of any positive correlation between the outcomes of successive shots. In fact a hit and then miss was actually a bit likelier than a sequence of two or more shots."
There you go. My answer is that statistically, the chances of a continuation of a 6 or 12 month trend cannot be gauged with any accuracy using technical analysis. You are better off making that decision based on your understanding of the underlying fundamentals of the business.
My 2c worth.
Now watch the onslaught from chartists and other market soothsayers.
