# This Just In: Teenage Virgins . . . NOT! Elsewhere, Pope Suspected to Be Catholic. **URL:** \ **Category:** The BBQ Pit\ **Created:** [March 10, 2004, 6:51pm UTC](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524 "2004-03-10T18:51:45Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![Ilsa\_Lund](https://avatars.discourse-cdn.com/v4/letter/i/a6a055/32.png) [@Ilsa\_Lund](https://boards.straightdope.com/u/Ilsa_Lund)\ **Post date:** [March 11, 2004, 5:52pm UTC](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524/21 "2004-03-11T17:52:54Z")
> [@Ilsa\_Lund](#): > > Indeed, quite right. If you care to take my word for it, I’m not completely ignorant of basic statistics. I actually have a concentration in biostatistics, I just don’t deal with them on a theoretical basis that often. It is inexcusable that I so egregiously confused the basic principles. :o > > Does not the confidence level indicate the probability that the sample is representative of the popuation? In other words, [how certain you can be that your data is representative of the population?](http://www.surveysystem.com/sscalc.htm) Or in exactly the same words, as the case may be. ---
**Author:** ![IzzyR](https://avatars.discourse-cdn.com/v4/letter/i/2acd7d/32.png) [@IzzyR](https://boards.straightdope.com/u/IzzyR)\ **Post date:** [March 11, 2004, 6:36pm UTC](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524/22 "2004-03-11T18:36:44Z")
> [@Ilsa\_Lund](#): > > Does not the confidence level indicate the probability that the sample is representative of the popuation? In other words, [how certain you can be that your data is representative of the population?](http://www.surveysystem.com/sscalc.htm) You left some key words out of your cite. “as precisely as needed”. IOW, the results will be accurate at the confidence level within the confidence interval. So again, if you measure and find a 3 point difference but your confidence interval (at the desired confidence level) is 4 points either way, you can only say at that level of confidence that the difference among the actual population is 3±4, or the interval of (-1,7). You cannot say in such a case that you’ve shown a difference, but you certainly can’t say that you’ve shown no difference either. ---
**Author:** ![Ilsa\_Lund](https://avatars.discourse-cdn.com/v4/letter/i/a6a055/32.png) [@Ilsa\_Lund](https://boards.straightdope.com/u/Ilsa_Lund)\ **Post date:** [March 11, 2004, 6:47pm UTC](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524/23 "2004-03-11T18:47:21Z")
> [@IzzyR](#): > > You left some key words out of your cite. “as precisely as needed”. IOW, the results will be accurate at the confidence level within the confidence interval. > > So again, if you measure and find a 3 point difference but your confidence interval (at the desired confidence level) is 4 points either way, you can only say at that level of confidence that the difference among the actual population is 3±4, or the interval of (-1,7). You cannot say in such a case that you’ve shown a difference, but you certainly can’t say that you’ve shown no difference either. The problem that was arising in my mind was that I am used to saying “No significant difference was found at alpha equal to .05. Thus the null hypothesis that no difference was present was accepted.” I understand the point you were making now. ---
**Author:** ![askeptic](https://avatars.discourse-cdn.com/v4/letter/a/eb9ed0/32.png) [@askeptic](https://boards.straightdope.com/u/askeptic)\ **Post date:** [March 11, 2004, 7:35pm UTC](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524/24 "2004-03-11T19:35:15Z")
How the fuck did a question about kids fucking turn into a pissing contest between two kids taking a class in statistics? ---
**Author:** ![litost](https://avatars.discourse-cdn.com/v4/letter/l/c4cdca/32.png) [@litost](https://boards.straightdope.com/u/litost)\ **Post date:** [March 11, 2004, 8:29pm UTC](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524/25 "2004-03-11T20:29:12Z")
> [@Ilsa\_Lund](#): > > The problem that was arising in my mind was that I am used to saying “No significant difference was found at alpha equal to .05. Thus the null hypothesis that no difference was present was accepted.” I understand the point you were making now. To nitpick, we either reject or “fail to reject” the null hypothesis (difference between two population parameters is zero). I didn’t understand your response to my prior post. What do you mean by “Not confidence intervals, probability levels.” alpha has everything to do with confidence intervals and hypothesis testing (alpha denotes the Type I error, the probability of incorrectly rejecting the null hypothesis). Are you confusing likelihood with confidence intervals? ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [March 11, 2004, 8:41pm UTC](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524/26 "2004-03-11T20:41:58Z")
I think they both are confusing sampling with hypothesis testing. It is not clear from the NY Times article which hypothesis was being tested, but let’s say it is that the pledges lower the rate of STDs. (And this would have to be in a specific time interval). It seems that this hypothesis was rejected by the study, and some p which was not given. On the other hand, we could ask what is the rate of STDs for populations taking and not taking the pledge. Then you use sampling theory to choose the samples. We can find confidence levels around the results for both populations using well known formulas. If the confidence intervals overlap, one might be tempted to say there is no difference, but I’m not sure that this is a valid conclusion. Hypothesis testing seems a better way to proceed, especially because one might be tempted to pick and choose results for a whole bunch of values, which is not valid. so, you can’t look through the data and claim that it shows that Asian computer nerds who don’t sign the pledge have lower rates of STDs than those who do. You need a new study for that. You especially can’t discard data you don’t like, which no one in this thread has done, but which seems to be SOP for politicians. ---
**Author:** ![Ilsa\_Lund](https://avatars.discourse-cdn.com/v4/letter/i/a6a055/32.png) [@Ilsa\_Lund](https://boards.straightdope.com/u/Ilsa_Lund)\ **Post date:** [March 12, 2004, 12:10am UTC](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524/27 "2004-03-12T00:10:36Z")
> [@](#): > > Are you confusing likelihood with confidence intervals? I’m confusing everyhting with everything. I’m preparing to defend my thesis, and the nonparametric Kaplan Meier survival analysis is fucking with my head. [Previous page](https://boards.straightdope.com/t/this-just-in-teenage-virgins-not-elsewhere-pope-suspected-to-be-catholic/233524.md?page=1)