calculated from negative present earnings are viewed with skepticism as almost meaningless, other than as an indication of high investment risk. Criticism The PEG ratio is commonly used and provided by numerous sources of financial and stock information. Despite its wide use, the PEG ratio is only a rough rule of thumb. Criticisms of the PEG ratio include that it is an oversimplified ratio that fails to usefully relate the price/earnings ratio to growth because it fails to factor in return on equity (ROE) or the required return factor (T). When the PEG is quoted in public sources it makes a great deal of difference whether the earnings used in calculating the PEG is the past year's EPS, the estimated future year's EPS, or even selected analysts' speculative estimates of growth over the next five years. Use of the coming year's expected growth rate is considered preferable as the most reliable of the future-looking estimates. Yet which growth rate was selected for calculating a particular published PEG ratio may not be clear, or may require a close reading of the footnotes for the given figure. The PEG ratio's validity is particularly questionable when used to compare companies expecting high growth with those expecting low-growth, or to compare companies with high P/E with those with a low P/E. It is more apt to be considered when comparing so-called growth companies (those growing earnings significantly faster than the market). Growth rate numbers are expected to come from an impartial source. This may be from an analyst, whose job it is to be objective, or the investor's own analysis. Management is not impartial and it is assumed that their statements have a bit of puffery, going from a bit optimistic to completely implausible. This is not always true, since some managers tend to predict modest results only to have things come out better than claimed. A prudent investor should investigate for himself whether the estimates are reasonable, and what should be used to compare the stock price. PEG calculations based on five-year growth estimates are especially subject to over-optimistic growth projections by analysts, which on average are not achieved, and to discounting the risk of outright loss of invested capital. Advantages Investors may prefer the PEG ratio because it explicitly puts a value on the expected growth in earnings of a company. The PEG ratio can offer a suggestion of whether a company's