[Discussion] Skill-Testing Registration Question

[Darth Wong]

I need to decide what is a good level for the difficulty of the anti-spambot skill testing question on the user registration screen:

• What is 3 + 5?
• How many degrees are in 4pi radians? (this is the current question)
• Given the simple quadratic function y = 3x^2 + 2x - 5, solve for y = 0
• Given the simple quadratic function y = 3x^2 + 2x - 5, find the slope at x = 5
• Integrate the function y = cos x from 25 degrees to 45 degrees. Enter the numerical result.
• Calculate the maximum normal stress due to bending moment for a horizontal 2m long 10cm square cross-section cantilever beam which is attached to a rigid vertical wall and loaded with a 500kg weight suspended from its end. Give result in units of Pa.

Obviously, the more difficult the question is, the less likely that retards will sign up. But there will no doubt be questions about what is "reasonable". You can submit suggestions if you like, with a few caveats:

• The question must not be too long. We don't need a question taking up half the registration screen.
• The question must have a numerical answer. I can't do an automated string-compare on a worded answer.

[Surlethe]

Questions requiring some skill in mathematics are reasonable -- people unfamiliar with the concepts can look them up -- but questions that require me to look up concepts or break out textbooks are unreasonable.

More seriously, it depends on the level and specialization of knowledge where you want to draw a line. If you want only people with degrees in physics or engineering, then go with the last question. If you want to let in everyone who can count on his fingers (and has at least eight fingers), go with the first one. I'm inclined to think that it's reasonable to ask a registrant to demonstrate some knowledge of basic high school mathematics, so I'd go with one of the calculus ones, or ask one that requires only differential calculus but some research skills if one hasn't encountered it before, like evaluating a third-order Taylor expansion near a given point.

[The Duchess of Zeon]

I suggest something that's a bit tricky, but also reasonably straightforward, namely:

F(x) = 5000 - F(ab)cos(theta) = 0
F(y) = F(ab)sin(theta) + F(ac) = 0

Where sin and cos of theta are related as a 3/4/5 right triangle where 4 is the vertical component.

Input the values for F(ab) and F(ac).

That would force them to know both algaebra-level mathematics with a little very basic trig, and more crucially to use critical reasoning skills, rather than just plugging in numbers, but rather to recognize sin theta would equal 4/5 and cos theta would equal 3/5. Also both numbers result in endlessly repeating decimals, so specify the number of sigfigs required for the answer to be correct to make sure they can follow instructions (and at least know what sigfigs are).

[Darth Wong]

The answer must be a single number.

[RedImperator]

I'm inclined to think that it's reasonable to ask a registrant to demonstrate some knowledge of basic high school mathematics, so I'd go with one of the calculus ones, or ask one that requires only differential calculus but some research skills if one hasn't encountered it before, like evaluating a third-order Taylor expansion near a given point.

I could never in a million years answer a high school calculus question. I'm looking at this list Mike gave and I could only answer the first.

Is the point of this question to prevent spambots from signing up, or to provide a knowledge filter? Because if it's the first, I don't see any reason for something more difficult than simple arithmetic, or a basic algebra problem. If the idea is to provide some kind of gatekeeping function, keep in mind you'll be locking out people who could contribute who simply don't have the skills or never got a quality math education.

[Darth Wong]

Keep in mind that people can go look things up on Google, like a simple conversion from radians to degrees, the quadratic function, etc.

[Gil Hamilton]

I certainly wouldn't suggest
"Given the simple quadratic function y = 3x^2 + 2x - 5, solve for y = 0"
since that it has two correct values for x.

However, if our goal is simple anti-spambot warfare, the 3 + 5? question is adequate, unless spambot registration will actually do math. As long as it requires a conscious thought on the part of the person registering, that should be enough to stymie an automatic registering program. I don't see any reason why it should be any more difficult than "3 + 5 = ?".

[The Duchess of Zeon]

The answer must be a single number.

Well, to both make it simpler and to meet that requirement, how about specify that the answer provided must be for F(ab) and drop the F(y) portion since that would be extraneous? That sets up an extremely simple algaebra one-equation, one-unknown that does however require a bit of basic trig and reasoning skills, as they still must figure out that cos(theta) = 3/5.

[Darth Wong]

I certainly wouldn't suggest
"Given the simple quadratic function y = 3x^2 + 2x - 5, solve for y = 0"
since that it has two correct values for x.

Good point. I copied that function up from the subsequent question, but forgot to make it symmetrical about the y-axis.

However, if our goal is simple anti-spambot warfare, the 3 + 5? question is adequate, unless spambot registration will actually do math. As long as it requires a conscious thought on the part of the person registering, that should be enough to stymie an automatic registering program. I don't see any reason why it should be any more difficult than "3 + 5 = ?".

I do think Red makes a good point, in the sense that we've probably had plenty of users who provided constructive input without having much in the way of math skills. A calculus prerequisite (or any kind of advanced math of any sort) would probably eliminate large swathes of the existing user base.

[phongn]

I think something like question two should be fine - easy enough to google, harder for the more sophisticated bots to break.

[Gil Hamilton]

I think something like question two should be fine - easy enough to google, harder for the more sophisticated bots to break.

How sophisticated are such bots anyway? Will they look for things like 3 + 5 and put in the answer?

[phongn]

I think something like question two should be fine - easy enough to google, harder for the more sophisticated bots to break.

How sophisticated are such bots anyway? Will they look for things like 3 + 5 and put in the answer?

Some can, IIIRC.

[Mr Bean]

Three simple questions will do it

The following are simple logic questions to help prevent bots from signing up for the forums, if you can't answer any of them try Google.
1. 23 plus negative 4 (Or some other simple addition problem)=19

2. Complete this common phrase, Between the Devil and the Deep ____ Sea? =Blue

3. What year was the first Star wars movie released in? 1977

If you want an IQ test to lock out people at the door, I don't support it. If you want a simple set of questions anyone can google up in ten seconds I support that. Since bots can't quiet think that far ahead. And if their's a human double-checking he will be just as able to google something hard as something easy.

[Edi]

However, if our goal is simple anti-spambot warfare, the 3 + 5? question is adequate, unless spambot registration will actually do math. As long as it requires a conscious thought on the part of the person registering, that should be enough to stymie an automatic registering program. I don't see any reason why it should be any more difficult than "3 + 5 = ?".

I do think Red makes a good point, in the sense that we've probably had plenty of users who provided constructive input without having much in the way of math skills. A calculus prerequisite (or any kind of advanced math of any sort) would probably eliminate large swathes of the existing user base.

At one time I went to an engineering school (though I didn't graduate) and most of those questions would wipe me out since I studied the mathematics and physics parts in Finnish. My language skills make me look like a native speaker in everyday situations, but math terminology is completely unfamiliar to me and so is a lot of physics terminology as it relates to very specifics. I'd need a dictionary to fully understand the physics question with the stress forces to make sure I didn't make mistakes, though I think I got it right on the first try. The problem is by no means unique to me, we have a fairly large ESL (English as Second Language) membership here.

Something like the simple radian conversion or "x+3 = 7, what is x?" type stuff should be okay. Not difficult but does require some thought to do. You can also change the numbers every now as well as the letters, or move them around in the equation, which should fool most spambots.

Another kind of feasible question would be "When date did <event> happen?" and pick fairly famous events, birthdays or dates of death of significant people like Einstein or Hawking etc. Those are easy to check up via Google and so on and you have an endless supply of events to choose from. If you change the format of the date required such as ddmmyy, ddmmyyyy, yyyymmdd etc, it gives even more variety.

I think the objective was keeping out spambots, not legitimate users, so let's not make it too difficult.

[Ted C]

Given the simple quadratic function y = 3x^2 + 2x - 5, solve for y = 0

I like this one. It's actually painfully simple, yet not obviously so at a glance.

[RedImperator]

I think something like question two should be fine - easy enough to google, harder for the more sophisticated bots to break.

How sophisticated are such bots anyway? Will they look for things like 3 + 5 and put in the answer?

Some can, IIIRC.

Can they solve a word problem? As in "Jill has three apples. Jack gives her five more. How many apples does Jill have?"

[Edi]

Mike, another thing that I though of was that if you can make the registration page such that the trick question is randomly chosen from a large pool every time a new registration is initiated, much like the revolving sig pic, that would foil the bots completely. No idea if it's doable, though.

[GrandMasterTerwynn]

Can they solve a word problem? As in "Jill has three apples. Jack gives her five more. How many apples does Jill have?"

I imagine it'd be much harder for them to crack. The current skill-test question can be plugged directly into Google, which will spit out the answer in machine-readable format. The one you suggested, if plugged into Google, does not return a machine-readable result right at the top of the page, and is an easier problem for a human to solve by themselves. To make it a little more challenging, one could have:

Jill has three apples. Jack gives her five more. She eats one and gives two to John. How many apples does she have now?

[Surlethe]

I'll retract the idea that understanding basic calculus should be a prerequisite. It's not as reasonable as I first thought. One would think we do a good job banning the actual retards anyway.

[Darth Wong]

I like the idea of a simple word problem. For example: "A redneck is driving to meet his meth dealer, who is 36 miles away. He is driving his pickup truck at 75 miles per hour. How many minutes will it take him to get there? Round your answer to the nearest minute."

[The Duchess of Zeon]

I do rather like that word problem.

[Broomstick]

I'll retract the idea that understanding basic calculus should be a prerequisite. It's not as reasonable as I first thought.

I realize that to some basic calculus is "simple" but not to everyone - and in my case it wasn't for lack of trying. Took me three tries to get through trigonometry and I totally wiped on pre-calculus. Of those questions in the OP, I could answer the first two, the next two maybe (would take some time and effort on my part - I haven't had to solve anything like that for about 20 years so I'm definitely rusty), and the rest are quite beyond me. Yet someone around here saw fit to make me a senator.

I, too, like the word problems, especially GrandMasterTerwyn's and Darth Wong's. The math is simplistic, what is really required is some ability to think. That will screen out idiots who happen to have math skills but no common sense or ability to relate to reality. Oh, and reading comprehension, which is helpful as well, but it shouldn't be beyond the ability of those for whom English is a 2nd language and also have sufficient skill to communicate in the forum.

Pity you can't add something so that those with US based ISP addresses have to demonstrate an ability to convert English to metric units. Sure, I use an on-line converter, but so what? I know how to achieve the proper result, does it matter how I get it?

[Coyote]

A simple word problem would be sufficient, or even a trivia-based question like "what year did Star Wars debut?". Some of the problems being described here as "simple" or "painfully simple" I cannot even fathom how the components are supposed to be related to one another.

[Darth Wong]

Mea culpa. At times, I forget that basic calculus is, well, not considered "basic" by most of the population. For some reason I had convinced myself that everyone should be able to do it, since they teach basic calculus in high school. I considered the last question to be the "technical knowledge" test, and the other ones to simply test whether you had graduated high school. Unfortunately, I had lost sight of the fact that not everyone (or even a slim majority) actually takes those calculus courses in high school, or remembers what a quadratic equation is (is the quadratic equation even covered in mandatory math classes in high school any more?)

[Edi]

The QE should be covered, it's that basic. It is here anyway. But whether people remember it after not needing to use it for anything for ten years is a different story.