Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Comment Medical research (Score 1) 41

In medical research when we are comparing groups it is normal to specify the power/ do a power calculation

power is a measure of the risk of finding a result when none exists (falsely rejecting the null hypothesis)

the null hypothesis is that your two treatments are equal

more here:

Comment Re:You're either with us or you're a Russian! (Score 1) 123

The Clinton campaign /is/ criticizing Trump on the racism thing.

There are a few problems with that:

1. The people who are voting for him don't care. "He's racist? Yes? And? I'm racist too. Why *wouldn't* I want to vote for him?"

2. People with memories longer than a gnat's remember the whole "superpredators" bullshit. Calling Trump a racist is a bit kettle/pot.

3. The Clintons haven't been exactly minority friendly except when it's politically expedient. LGBTQI rights? Only in the past few years.

"You can't shake the Devil's hand and say you're only kidding" TMBG "Your Racist Friend"

The only one really qualified to call out Trump on racism and "othering" was given the finger by the DNC.

Trump is a bigot. He wears it on his sleeve. Hillary's bigotry is more covert. Hillary is only marginally better, and that's not saying much.


Comment Re:In other words (Score 1) 51

limited participation blockchain is redundant because the trust is already established by the exclusivity of the system.

Imagine that not all of the participants turn out to be honest. Or, imagine this is finance, and 0% of the participants are honest.

Majority-signing works well when the majority are honest, even if a substantial minority are not. It also works well when everyone is dishonest, but very unlikely to collude. This is solving a different problem than Bitcoin tries to solve. This is an implementation of "mutual auditing", not an alternative currency.

The thing that establishes trust on bitcoin is that no one miner can easily own a large portion of the compute power on the system,

Perhaps. I think it's possible the NSA has the compute power to take over bitcoin, After all the NSA had "ASIC miners" for at least 7 years before BTC existed. (You don't think the NSA published SHA-2 before they had ASICs, do you?)

Comment Re:Not a bad guess (Score 1) 135

Human population has expanded tremendously in the last part of those 800,000 years, and all of us consume oxygen.

It's worth remembering that Earth's total biomass is:
* 99.9% Prokaryote bacteria
* 0.1% Other (mostly plankton)

The tiny remainder that's not bacteria or plankton is mostly fish. Humans, sure, are reasonably successful within what's left over, but so are cattle, termites, ants, and krill.

Comment Re:Do away with them (Score 1) 78

Not sure what you actually mean when you say that SQL NULL means unknown but not absent? Is there a meaningful distinction you are making here?

It makes a difference when you start applying operations.

For example, if you compare a NULL to any value (even another NULL), the result is also NULL, rather than TRUE or FALSE. This doesn't make sense for absent values - two absent values should compare equal (and, indeed, two nulls in JS do). On the other hand, it makes perfect sense if NULL means unknown - if my last name is unknown, and your lastname is unknown, comparing them for equality can only produce "unknown" as a result, since it's not known whether they're the same or different.

Same thing with arithmetic operations. 1 + NULL equals NULL in SQL, again, because NULL is really "unknown", and so when you add an unknown value to 1, the result is also unknown. If NULL were an absent value, the expression should either produce an error, or give 1.

The most telling part, though, is the SQL truth table for Boolean operators that includes NULLs. Specifically:


Again, this makes perfect sense if and only if NULL means unknown. AND is always false if one of the operands is guaranteed to be false, so FALSE AND NULL is always false, regardless of what the actual unknown value is. On the other hand, FALSE AND NULL is NULL, because the result could be either false or true depending on the unknown value. With OR, it's the reverse - TRUE OR NULL is TRUE, because OR is always true if one of the operands is definitely true, regardless of what the other operand is. FALSE OR NULL is NULL because the result depends on the unknown value.

Philosophically, the difference also exists. Absent value means "I know what the value is, and there isn't one". For example, for a guy from Iceland, you know his last name - he doesn't have one. Unknown value means "I don't know what the value is, and there could be one". For example, you don't know if I'm from Iceland or not, so I may or may not have a last name, and you don't know which one if I do. These are two distinct states, and ought to be reflected as such in the database.

Comment Re:Why do people care... (Score 1) 73

If a person wants or expects privacy, I believe that the onus is upon them to take measures to sufficient degree

They do. They beat the crap out of glassholes. Sufficient measures thus taken, effective privacy is restored.

)there's no rational basis to be worried about it

Says you. Most people see it differently.

When I want privacy, I go somewhere private. I step outside, however... and it's fair game.

Says you. Most people see it differently.

Comment Re:In other words (Score 2) 51

In other words: They are doing something completely different, but still call it "blockchain" because that's the current buzzword.

A blockchain with limited participants is still a blockchain. It's as trustworthy as those participants. If the participants all trust one another, or trust the system to protect them from the others, it serves its purpose, even if they are in fact pathologically lying shitsacks like financial companies.

I'm dubious of the "editing", but if it's really just new records that say "this record replaces record XYZ", i.e., it's still write-only except by convention, that's fine too.

Reminds be a bit of what "cloud" should have stood for until it became a generic moniker for simple online storage.

Not sure what you mean here. Sure lots of marketeers talk about "stored in the cloud", but most often that does mean "stored with AWS or Azure, behind the scenes". And there's plenty of "cloud computing" too: more and more distributed scientific jobs are moving that way, as well as naturally-distributed work like animation rendering. Heck, it's the new fad for small software companies to build and test jobs in the cloud.

Slashdot Top Deals

Real Users are afraid they'll break the machine -- but they're never afraid to break your face.