At the risk of being meta; I think you should vote up when someone contributes to a discussion in a meaningful way, regardless of server you agree or not.
While it is good to look at these sorts of mathematically rigorous algorithms, I think I would be frustrated if it was used everywhere. Or, well, maybe not me perhaps, but a non technical user.
The beauty of the second algorithm for rating products is that it is straightforward. Having never seen it before I can deduce that 5 stars come before 4 stars and more reviews come before fewer. If I want to skip ahead to the 4 stars I know what to do. I can internalize the sorting algorithm easily. And as a user, understanding the order items are presented to me is important.
If Amazon were to use the last algorithm and present items in that order (assuming we accounted for the 5 star vs positive/negative issue), it would like a random order to most users and would be frustrating.
So I guess what I am saying is that this algorithm is very clever, but in some cases, it may be too clever. Sometimes you just want to keep it Simple Stupid.
The second algorithm, in my experience, is too simple, though. When browsing Amazon I'm pretty regularly annoyed by an item with one 5* review appearing ahead of an item with hundreds of 4* and 5* reviews.
One simple fix would be to avoid calculating an average until a minimum number of ratings have been given. But I do think the statistical way is lovely. If I were Amazon I'd give it some kind of snappy trademarked name and push it as a feature.
Instead of displaying stars, Amazon could display a percentage, which under the hood represents the Wilson confidence number. It would be totally intuitive to browse: first come all the 100% items, then the 99's, and so on.
The point is we have to determine how to define a five-star item, a four-star one, etc. Currently, an Amazon item's star value is the average of the star values of every review. The author is saying that that's a bad way to compute the item's star value. The author would argue an item with only two reviews that are both fives should have a lower star value than an item with 400 fives and 1 four. We typically associate stars with the averaging algorithm (i.e. we define an item's star value as the average of the star values of its reviews), so it might help if we do away with the notion that each item has a star value, and just think of this as saying an item with 400 reviews of 5 stars and 1 review of 4 stars should be shown before an item that just has 2 reviews of 5 stars.
Currently, when we see an item's star value, we think of it as an indicator of the quality of the item. But if it's just the average of the star values of every review, the author would argue that we're not going to get an accurate indicator of quality. The author argues that whether the quality indicator of an item is expressed in stars or percentages, that value should be determined by the third algorithm, not the second, and that the order the items are shown in should be the result of sorting those quality indicators.
But how is Simple Stupid in the Amazon case a better output for the user? Do you, as an Amazon shopper, really believe that the item with one 5-star review is a better bet for you than the item with 580 reviews and an average of 4.5-stars?
I don't, but I can intuitively grasp that a 5-star item with 2 reviews is not reliable. Since I understand how the sorting works, I know I have to jump to the 4.5 star items in order and check how many reviews that item has and if it also has a small number then I will jump to the 4 star items.
The point is, I understand the sorting order and can manipulate them if I am not satisfied with what is presented to me. Having a very esoteric algorithm is a risk. Maybe you'll present just what the user really wanted. But if you get it wrong they will be lost to do anything about it. I tend to dislike systems that leave users helpless when something goes wrong.
Not to detract from your main point, but I don't think Siesta is very common in Mexico and most other Latin American countries. I was born in Cuba, lived there for five years and lived in Mexico for about three or four. I don't know of a single person who regularly slept after noon.
In fact, I had an opportunity to live in Barcelona for three months and while a lot of businesses do close down from noon to three, I got the impression that people were not using that time to sleep, and that the idea of siesta in Catalunya is on the decline.
Ok, I did work for Bolivia for a time, and our Bolivian office closed for siesta, as did our main customer (the La Paz city council).
Same for a more rural area of Mexico (Toluca surroundings), they also did siestas there.
Googling a bit, acording to Time magazine, siesta was struck down in Mexico in 1944, so it's more a myth than reality now I guess (probably subsists in some more rural areas).
My impression was that siesta still persisted in some countries, but that it tends to disappear as they conform to western work hours, and, as the Time article states, it does involve four commutes instead of two, so it's not workable in urban areas (btw, people who siesta still work the same amount of hours, I'm not saying they work less).
I couldn't help but notice a resemblance between what you are describing and a lot of machine learning algorithms.
It seems like the most successful ML algorithms are self-correcting ones, rather than ones that attempt to calculate the exact correct answer in one go.
The 25% he alludes to is your recurring mortgage payment, which also happens annually--monthly, actually. What he means here is that a discount of 5% in your mortgage negotiations is much less than an increase of 5% in your salary. So he is right, for the right reason.
corin_ is right - salary is recurring, mortgage/real estate purchase is one-time. You pay off the mortgage with recurring payments, but they are based on the one-time amount. If you negotiate $10k extra salary, after two years you will have $20k extra. If you negotiate $10k lower real estate purchase, after two years you will not have $20k extra. (Technically you will have a little bit more than $10k extra due to compound interest on smaller principal, but nowhere near $20k.)
The sort of animations intended to teach remind me of the RSA animation which are excellent and I highly recommend them:
http://www.youtube.com/user/theRSAorg
I agree. I've also found people with hobbies that are dangerous tend to be more mature. For example, people that go hiking, rock climbing, etc... I am not sure why and I am wary of saying it is because stupidity will get you killed in those situations and a more serious outlook serves you well, but that is one possible reason.
It takes serious planning and visualization over several years to excel at a demanding hobby. It requires dedication for the sake of its intrinsic rewards. These sorts of hobbies rarely have the potential to "turn into a business." Any serious practitioner has effectively self-selected as a person who has the means, makes the time, and has a passion for the pursuit of personal fulfillment.
+1 for wording it so well. I might add that it also takes a person who is willing to accept full responsibility for his actions and the actions of others in his group since nature takes no excuses.
