this is one method to value companies which have no revenues or earnings; or book value is low relative to intrinsic value; or success is difficult to forecast; or for stocks that are easily hyped.
other questions: how big is the target market?
what is the estimate of the company's possible market share?
what is its cash burn rate?
here's a possible solution:
stock price x number of shares = total market cap
total r and d spending = for the last 5 years including the present year
divide the total market cap by the total r and d spending
possibly adjust the figures for so-called "wasted" r and d spending in an attempt to be conservative:
valuation = possible attractive investment = a number under 5
a fair valuation = a number around 10
a high valuation = a number of about 15x to 20x or more