September 29, 2013 at 3:02 pm
Oh dear....
If I may change the topic... For the purposes of a book chapter, what are your favourite statistics-related myths?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
September 29, 2013 at 3:04 pm
Jeff Moden (9/29/2013)
I'm am totally afraid for this person...http://www.sqlservercentral.com/Forums/Topic1499747-391-1.aspx
For this person or for his/her company?
September 29, 2013 at 3:12 pm
GilaMonster (9/29/2013)
Oh dear....If I may change the topic... For the purposes of a book chapter, what are your favourite statistics-related myths?
1. People that think that Temp Tables don't have them.
2. People that think they don't need to be maintained because auto-update statistics is turned on... especially when it comes to tables with millions of rows.
--Jeff Moden
Change is inevitable... Change for the better is not.
September 29, 2013 at 3:14 pm
Luis Cazares (9/29/2013)
Jeff Moden (9/29/2013)
I'm am totally afraid for this person...http://www.sqlservercentral.com/Forums/Topic1499747-391-1.aspx
For this person or for his/her company?
Yes! 😉
--Jeff Moden
Change is inevitable... Change for the better is not.
September 29, 2013 at 5:40 pm
GilaMonster (9/29/2013)
Oh dear....If I may change the topic... For the purposes of a book chapter, what are your favourite statistics-related myths?
As 2013 is the International Year of Statistics, I'll assume you are talking about that science (or art) :alien: rather than about table statistics. :Whistling:
You might find the myths and realities[/o] page thatGuanajuayto U's maths research center put together for the international year of statistics helpful; or not, it may not be the sort of myth you are looking for. I have some more technical statistics myths, though:-
1) With a normal distribution there's a central band 3 standard deviations wide that contains 99.7% of the population. (It's actually 6 standard deviationw wide - the 3 sigma rule isays that 99.7% are within 3 standard deviations of the mean).
2) It's always safe to assume that everything has a normal distribution, because any other distribution is abnormal. That's just total nonense; plenty of things in the real world conform to Exponential distributions, Bounded Uniform distributions, Poisson distributions, Cauchy distributions, Weibull distributions, Pareto distributions, Erlang and other Gamma distributions, and hordes more.
3) The Shannon Hartley sampling theorem proves that you can only get 2B bits/second down a channel of bandwidth B Hertz, no matter how good the signal to noise ratio. (It actually says 2B real numbers to exact precision, ie 2B times an infinite number of bits; but I've had people with engineering degrees who worked in data communications making this claim, and been unable to convince them they were wrong; it says very little for the insititutions awarding those degrees that they delivered pig-headedly stupid graduates who didn't know the diffeence between a bit and a baud, and couldn't handle enough statistics to understand Shannon's encoding theorem).
4) You are always saffe using the law of large numbers. Well, you certainlty aren't when looking at specrum splitting and shifting due to electrostatic effects, or resonance energy distributions at the quantum level, or a few other bits of physics (some of it applied physics, not just theeory) where Cauchy distributions crop up.
5) Every statistical distribution has a mean and a variance; well, Cauchy distributions have neither, nor any higher moments, and that's why number 4 above is a myth.
6) If statistics predicts that something has low probability and then that something happens this proves statistics is wrong. (Interesting idea that; so low probability events don't happen? The favorite always comes first?) Theres also a similar one about high proability events that don't happen.
Tom
September 29, 2013 at 6:32 pm
*sigh*
🙂
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
September 30, 2013 at 5:50 am
hisakimatama (9/27/2013)
Rawr! I did it! Worked a full 8 hours on the stupid query that made me quite grumpy yesterday, converting it into a much better SQL statement and routing it through SSRS instead. Execution time for the report on a heavy-workload project is about 10 seconds, so not overly bad; previously, the same project took 10-15 minutes, so this is much, much better. Kicked the NOLOCK junk out of the query, too, which seemed like it was there to offset the completely unnecessary burden created by the DISTINCT. Would've liked to solve the problem faster, but figuring the logic of the query out was infinitely less intuitive than I would've liked :hehe:.Grant, it looks like the guy you were mentioning earlier has backed off on his stance on NOLOCK, so I don't think I need to DBCC TIMEWARP back to when his horse was still alive to give it a valid beating at present. Would you like me to chime in over there anyhow? I can round up a fresh batch of hamster poo for fuel for added accuracy 🙂
It can't hurt. Someone else will find that thread through searches. They might as well see that it's a true thing in production.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning
September 30, 2013 at 5:51 am
Lynn Pettis (9/29/2013)
I am officially a grandfather, again. Kassondra gave birth to her second son, Branson James on 9/28 @ 6:19 PM MDT!
Congrats Granddad.
"The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
- Theodore Roosevelt
Author of:
SQL Server Execution Plans
SQL Server Query Performance Tuning
September 30, 2013 at 6:05 am
Grant Fritchey (9/30/2013)
Lynn Pettis (9/29/2013)
I am officially a grandfather, again. Kassondra gave birth to her second son, Branson James on 9/28 @ 6:19 PM MDT!Congrats Granddad.
Congrats, indeed.
September 30, 2013 at 6:47 am
Brandie Tarvin (9/30/2013)
Grant Fritchey (9/30/2013)
Lynn Pettis (9/29/2013)
I am officially a grandfather, again. Kassondra gave birth to her second son, Branson James on 9/28 @ 6:19 PM MDT!Congrats Granddad.
Congrats, indeed.
Congratulations, Lynn. I hope mother and baby are both doing well.
September 30, 2013 at 6:48 am
Jeff Moden (9/28/2013)
GilaMonster (9/28/2013)
Jeff Moden (9/27/2013)
Speaking of "Are the posted questions getting worse"?... I was going through some old responses to some posts and I came across this one that no one responded to...After googling, i have learnt to open a new clr stored procedure project to convert rtf format. But as i told, i have no knowledge..So could you please guide me from here?
First, I congratulate everyone for not responding to that post because even I have my limits and had to make a conscious effort to not respond to it with less than subtle hints about using tools they don't know anything about and maybe a rant about having other people do their job for them.
The economy must be picking up because I'm seeing more and more "I have no knowledge {of SQL}" types of posts across the board. Apparently, more and more people are getting themselves hired with "no knowledge". I blame the interviewers for this type of thing.
Have you folks observed the same kind of thing over the last month or so or is it just me?
Have you seen the myriad of dynamic SQL related questions the last few days?
Heh... between that and TempDB questions (and some of the answers, apparently... 50MB) by people who have "no knowledge", it's been a real hoot.
I would say that it depends on where you are. In New England the unemployment rate is ~2% in IT and there are a lot of SQL Server jobs open. I'd also venture to say that the 2% are probably not top-notch or are new graduates who have unrealistic compensation expectations for their first job. Employers are still trying to low-ball people, which is why positions stay open in New England. No ones moving to a new job without a decent increase.
Also in the US, pretty much all the consultants I know have enough work and are actually looking for help in many cases. Case in point is Brent Ozar Unlimited adding an employee.
Jack Corbett
Consultant - Straight Path Solutions
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September 30, 2013 at 6:51 am
Lynn Pettis (9/29/2013)
I am officially a grandfather, again. Kassondra gave birth to her second son, Branson James on 9/28 @ 6:19 PM MDT!
Congrats grampa! I'm hoping I'm at least 10 more years before being a grandfather.
Jack Corbett
Consultant - Straight Path Solutions
Check out these links on how to get faster and more accurate answers:
Forum Etiquette: How to post data/code on a forum to get the best help
Need an Answer? Actually, No ... You Need a Question
September 30, 2013 at 6:55 am
Wish it was like that here. Was an unexpected slump late May, early June. I'm not the only one seeing it. Have two friends, one has just found his first contract since March, the other has accepted a crap job that he hates because it's all he could find.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
September 30, 2013 at 6:59 am
GilaMonster (9/27/2013)
Thursday at Summit is going to be sooo funny. Just saying...
Okay, I need some more info on this one. I don't see anything on the schedule that funny going on Thursday.
Jack Corbett
Consultant - Straight Path Solutions
Check out these links on how to get faster and more accurate answers:
Forum Etiquette: How to post data/code on a forum to get the best help
Need an Answer? Actually, No ... You Need a Question
September 30, 2013 at 7:19 am
Jack Corbett (9/30/2013)
GilaMonster (9/27/2013)
Thursday at Summit is going to be sooo funny. Just saying...Okay, I need some more info on this one. I don't see anything on the schedule that funny going on Thursday.
I didn't say there was something funny on the Thursday schedule. 🙂
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability
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