She found that parents' time cost is larger, on average, than direct spending, at least until children reach age 12.

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Of course, if your aim is to dollar-cost average your share purchases over a long period of time, this is not a factor.

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George Scangos, the chief executive of Biogen Idec, pointed out that although the process of inventing new drugs has been getting exponentially more expensive for years, the cost of developing the average new drug seems to be flattening out for the first time in decades.

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The second-ranked airline in terms of overall quality was low-cost airline Jet Blue, which posted better than average performance in terms of on-time arrivals, mishandled bags and customer complaints.

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On its Compare Care Line, a Bellin financial adviser provides an average cost from the previous six months for a given procedure and the price range over that time period.

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Joe saves this same amount annually until age 70 and earns an average compound annual return over that time of 6% by investing in a balanced mix of low-cost stock and bond mutual funds.

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By setting up a few simple Excel formulas (nothing more complicated than addition and division, you can see what they look like in this sample spreadsheet), you can not only track your maintenance data (what the mechanics did, when they did it, how much it cost, and what the mileage was at the time) but also see your average daily mileage during each period between servicings.

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At the same time, Spirit pointed out, there was a 14.5 percent increase in the average economic fuel cost per gallon compared with the same period a year earlier.

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This was just one of the many advantages Dell enjoyed during this time, which enabled it to charge higher prices and make PCs at a lower than industry-average cost.

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