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## Comment Re:It Will Pay Off in 9 Years (Score 2, Informative)591

Total return is \$133,600 on \$37,000 investment, so 3600% Return on Investment over 30 years.

I assume this was a typo for 360%. Of course, calculating total return like that is a pretty horrible way to measure whether a long-term investment is worth it. A better way is this method:

If you invested that money in a compound interest account (either savings or some investment with an average annual return reinvested), you'd have to get 15.43% annual compound interest to turn \$37K into \$136K in 30 years.

But you messed it up somehow... by a LOT. The actual number is slightly under 4.4%. You can verify it like so: since you gain 4.4% compounded each year, calculate \$37k * (1.044) * (1.044) ..., 30 times, for a total of \$37k * (1.044^30), which is about \$134k.

Still, 4.4% isn't bad. Good luck earning that on rolling CDs, even if you go with 5-year. It's also inflation-protected, since any decrease in dollar-value means nominal utility costs go up, which means you save "more" and your percentage nominal return goes up. I don't think it's quite good enough of a return to make it worth it, but it depends what your alternatives are for your money. If you have an outstanding loan/mortgage of more than that, and you don't think lots of inflation is coming, then you probably want to pay off the loan before investing in this. Paying off a loan is like making a risk-free compound-interest investment at whatever your loan rate is, whereas these solar panels have an uncertain return that depends on electricity rates, lifetime estimates, hell even climate change! Of course, inflation probably IS coming, in a big way, but that's a completely different story...

This all assumes a purely financial perspective. If you derive personal value from "living green," then you'd have to add that in. 4.4% is a bare minimum return.

Btw, other parts of your post are dead on. Taking out a mortgage to do improvements to your house like this is pretty much the ideal way to do it... you don't see much change in day-to-day cash flows, and even if you have to sell the house early, the presence of a solar panel setup will increase the value by (more than) enough to cover paying back the extra loan principal. And if you expect inflation, taking out a loan is ideal. You get to pay it back with future-dollars-that-are-worth-less.

## Comment Re:A mugger speaks... (Score 1)315

Someone walking a couple blocks from a restaurant back to their car is not going to have their night vision. They won't see anyone moving around in the dark. Nor will they have much night vision for a while after they get in their car and start driving, which has an impact on the safety of pedestrians, and cyclists that don't have lights.

## Comment Re:I Wonder Why... (Score 1)333

I've looked into OpenID multiple times before, and each time wandered around in a maze of terminology and things that didn't make any sense to me until I gave up.

I'm sure it's better overall than the current system of username/password pairs, but it's just not better enough. Pretty much any complaint about the current system can be solved in a way that doesn't depend on anyone else implementing or supporting it, and which is less complex than OpenID. If there were compelling enough advantages to using OpenID, I might have gone ahead and tried even though I didn't understand which parties were responsible for which parts of the authentication, or even how many parties were involved... but I just don't see the point, and it's not for lack of trying.

## Comment Re:What sort of a bloody name is Zavvi anyway?! (Score 2, Insightful)221

I guess that's the theory (though I'm not clear if is this accepted practice or your own reasoning; if you're an economics genius, please accept my apologies- it doesn't matter which ;)).

I'm no genius, and I not sure what group I would be speaking for if I said it was "accepted," but I have studied economics and I work with these issues as part of my job at a large insurance company. I do a lot of basic financial modeling, and work with the people in the investment and hedging areas that do the more advanced stuff. Regardless, you shouldn't take arguments like this at face value from anyone (especially on the internets), and I'd be glad to explain the reasoning behind my conclusion.

There's a couple different ways to define inflation, which does make this a bit (as you say) complicated. As a financial professional, I tend to think of the exchange rates as representing the relative prices of two currencies, and inflation of one currency as a decrease in that price, because that's the most consistent and tractable way to model uncertain future inflation and exchange rates. You're absolutely right that the presence of a free global market with minimal trade barriers (artificial or otherwise) is required for this to match the "cost-of-living" interpretation of inflation. If you measure inflation as the cost of goods for which there is such a market, such as widely-traded commodities like gold, then what I said should hold. If you define inflation as a CPI on an arbitrary basket of goods, some of which don't have such a market, well... that's what I meant about "not actually measuring inflation." Not in a consistent and useful way.

If I'd done the conversion a few months ago, when the Pound Sterling was hovering around the US \$2 mark, you'd have got a higher figure than if I'd done the same thing today.

Not if you measure inflation based only on internationally traded commodities. If the Pound has lost value relative to the Dollar since then, then either it cannot buy as many commodities (inflation), or the Dollar can buy more (deflation), or both. Either way, it shouldn't matter what date you choose for the currency conversion, because the proper inflation adjustment will get you to the same place.

This is a bit confusing for people who are used to thinking of inflation only in terms of an arbitrary consumer price index. You might think that if you are making the same number of Pounds, and it buys the same number of CDs, what inflation has occurred? If your CPI basket consisted entirely of CDs, then indeed it would show 0% inflation. However, that's misleading, because you presumably spend money on many things which are ultimately driven by commodity prices and international free trade. Even if you don't, the suppliers of the CDs probably do, which means that even though you're still paying them the same for the CDs, they are feeling the true difference in price.

In other words, despite the stable salary and CD prices, I would say that the Pound really was worth more (relative to the Dollar) a few months ago, so your £X,000 salary and £X cost of CD were both "more" than they are now, even if the only thing you actually bought with your salary was CDs. You were still paying the opportunity cost by choosing CDs over whatever alternatives you had for that salary. Since then, you've received a pay cut (by being paid the same number of a less valuable currency), and certain goods (CDs) but not others (commodities) have also been discounted in the same way. If you still buy only CDs, you'll get the same number of them, but you won't be paying as large of an opportunity cost to do so, since your salary couldn't have bought you as many other goods. (Alternatively, or perhaps additionally, I've received a raise, but many goods like CDs have correspondingly gone up in price.)

This implicit price change can only happen if there are significant barriers to free international trade of the good in question, because otherwise someone could buy up CDs in one country, sell them in another, and convert the currency back to the original at a profit. In fact, this mechanism is exactly what makes the commodity prices a consistent measure. If the exchanges rates of the currencies didn't match up with their inflation (the amount of commodities they could buy), then people would do this trade until the values lined up again. That's how I can be so confident in the practical application of theory, as long as "inflation" is defined that way.

If you try to have a definition of inflation that relates your salary to your consumer prices of specific goods, then if any goods have higher barriers than others, you can simultaneously have "inflation" relative to some goods but not others. I find that to be a pretty useless way to think of value and inflation.

## Comment Re:What sort of a bloody name is Zavvi anyway?! (Score 2, Informative)221

(*) Side note: What's the accepted method for showing a historical price in another currency in today's terms? Do I convert pounds to dollars at (e.g.) 1995 rates first *then* factor in dollar inflation. Or do I factor in pound inflation first then convert from pounds to dollars at modern-day rates?

I've never heard of one or the other being preferred (most journalists probably don't even understand the difference), but you should get approximately the same result either way. Inflation of one currency more than another changes the exchange rate correspondingly. If you don't get the same result, then one of the measures you used for inflation is not actually measuring inflation in the way you want. (For example, the CPI as published by the BLS probably understates the true amount of currency inflation, for political reasons.)

## Android Also Comes With a Kill-Switch300

Aviran writes "The search giant is retaining the right to delete applications from Android handsets on a whim. Unlike Apple, the company has made no attempt to hide its intentions, and includes the details in the Android Market terms and conditions, as spotted by Computer World: 'Google may discover a product that violates the developer distribution agreement... in such an instance, Google retains the right to remotely remove those applications from your device at its sole discretion.'"

## Submission + - Ultra Dense Optical Storage -- On One Photon

brian0918 writes: "Researchers at the University of Rochester have developed a way to encode an entire image's worth of data into a single photon, store it, and retrieve the image intact. From the article: 'To produce the UR image, Howell simply shone a beam of light through a stencil with the U and R etched out. He turned down the light so much that a single photon was all that passed through the stencil. Quantum mechanics dictates some strange things at that scale, so that bit of light could be thought of as both a particle and a wave. As a wave, it passed through all parts of the stencil at once, carrying the 'shadow' of the UR with it. The pulse of light then entered a four-inch cell of cesium gas at a warm 100 degrees Celsius, where it was slowed and compressed, allowing many pulses to fit inside the small tube at the same time."

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