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Alpha risk beta risk

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Viewing 69 posts - 1 through 69 (of 69 total)
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  • #46423

    Rakesh
    Participant

    Hi,
    I want to get a clearer picture of the relation between Alpha risk, beta risk & sampling. The theoritical concept/significance of considering the said risk while selecting a sample.
    Till now I have been doing sample size selection using a sample calculator.

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    #153369

    Adrian P. Smith
    Participant

    Hi Rakesh
    Alpha risk is the risk you are willing to take of making a wrong decision. It is the decision point for your p value: if p < alpha you reject the null hypothesis.
    Alpha risk is therefore the maximum risk you are prepared to take of rejecting the null hypothesis when in fact it is true. This is often called the Producer’s Risk, since the producer runs the risk of scrapping a product which is in fact good. Rejecting the null hypothesis when it is in fact true is also called a Type I error
    Clearly, the more risk averse you are (the lower alpha risk) the more data you will need to prove that an observed difference is not due to chance (larger sample size).
    The classic example of this is convicting an innocent defendant. If your alpha risk is .05 you have a 5% chance of convicting an innocent. The more sure your want to be that the person is guilty, the more evidence you will need to present.
    Beta risk is the other side of the coin. It is the risk of acquitting a guilty man. (1 – beta) is also called the “power” of the statistical test and is the probability of detecting a difference which does in fact exist.
    Not rejecting the null hypothesis when in fact it is false is also called a Type II error or the consumer risk (risk that the producer will ship faulty goods).
    So just like the alpha risk, the lower the beta risk the more data you will need and therefore larger the sample size required.
    Alpha risk is always fixed by the “statistician” before performing the test. Beta risk is often assessed after the test has been performed in the event of a p value > aplha risk. I.e. the test is telling you the difference is not significant. Calculating the beta risk helps decide whether the difference really does not exist or whether it is worth spending money to collect more data. As a rule of thumb we look for the power to be 80%, therefore beta risk of 20% or 0.02.
    Hope this helps.
    Rgds,Adrian
    http://adrian.smith.name
     

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    #153413

    BC
    Participant

    Rakesh,
    I have an Excel file that I use to demonstrate the relationship between alpha, beta, and sample size.  It is both quantitative and graphical.  Mainly I use it for training/demos.  It isn’t exactly user-friendly but you sound like you understand the concept well enough.  Post your email and I’ll send it to you.

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    #154282

    Kedar K.
    Participant

    Send me the excel file regarding alpha an beta risk……

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    #154288

    Emilio
    Participant

    Rakesh,
    may I see your excell file ?
    Thank you in advance, Emilio
    @caliandro.eu">emilio@caliandro.eu
     

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    #154295

    BC
    Participant

    Kedar K.,
    Please post your email address.
    BC

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    #154522

    Quainoo
    Member

    Hello BC,
    I am also very intersted in this Excel file that you use to demonstrate the relationship between alpha and beta.
    Can you sen it to me ?
    If it is possible, I will send you my email.
    Many thanks
    Vincent
     

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    #154524

    Allthingsidiot O
    Participant

    An Excellent  elaboration

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    #154536

    Nag
    Participant

    Hai BC,
    I am  intersted in this Excel file that you use to demonstrate the relationship between alpha and beta.
    Can u plz send me the file.
    My mail ID is [email protected]
    Regards
    Nag

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    #154594

    Bill C
    Participant

    The best explanation I have seen is through the use of a dynamic illustration. (A JMP script that shows the relationship between alpha, beta, sample size, difference to detect, etc.) Maybe you could download a trial version of JMP and then test out the script. I am not sure if the scripts are free downloads from Predictum or not.
    http://www.predictum.com/index.html

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    #154598

    BC
    Participant

    Vincent,
    Please post your email and I’ll get it to you ASAP.
    BC

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    #154599

    BC
    Participant

    Bill,
    Absolutely agree.  Playing around with a graphical tool that shows alpha, beta, sample size, effect size, etc is the ONLY way to fully appreciate these relationships.  I haven’t tried the download you mention but I do use and Excel file in training and people “get it” with the demo and a little explanation.
    BC

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    #154607

    Bower Chiel
    Participant

    HiI’ve found Russ Lenth’s Java applets for power and sample size very useful in dealing with alpha and beta risks. They are available at: –
    http://www.cs.uiowa.edu/~rlenth/Power/Bower Chiel

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    #154669

    Quainoo
    Member

    Hello BC,
    This is very kind, thanks very much.
    My email is:    @aol.com">vincentp74@aol.com
    Vincent
     
     

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    #154671

    O’Connell
    Participant

    BC,
     
    If it’s not too much to ask can you forward along the excel file to me as well?
     
    [email protected]
     
    Thanks

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    #154676

    Interested
    Participant

    could you also send me a copy of your excel file. Many thanks.

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    #154679

    Rakesh
    Participant

    Hi BC,
    Please send the excel file to [email protected]. Iam still grappling with the issue.
    Regards.

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    #154733

    BC
    Participant

    Interested,
    I’d be happy to.  Please post your email.
    Thanks,
    BC

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    #154853

    Interested
    Participant

    please send to [email protected]

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    #164913

    Taylor
    Member

    BC,
    I agree with this post.  I am looking for just such an Excel based file for training purposes.  Can you send to @cat.com">hobbs_todd@cat.com.  (Don’t forget underscore: hobbs_todd)
    Thanks!

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    #166293

    Broomfield
    Participant

    BC,
    Can you please send me a copy of the Excel file that you use to demonstrate the relationship between alpha, beta, and sample size?
    email is [email protected]
    Thanks

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    #166541

    Viba
    Member

    Can you please send me a copy of the Excel file that you use to demonstrate the relationship between alpha, beta, and sample size?

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    #166599

    Babar
    Participant

    Can I please get that excel file the alpha and beta risk in detail.
    Thanks and regards,
    [email protected]

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    #167000

    Matthew
    Participant

    I would be very interested at seeing your Excel Macro for alpha and beta risk relationships to sample size.  Please mail it to me if you can. @hotmail.com">mhennick88@hotmail.com
     
    Thanks,
    Matt

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    #167996

    Moment
    Participant

    I’m really interested in Excel file for evaluating alpha/ beta risk. I hope it would help me understanding it completely. Please send it to me, if it’s possible, @hotmail.com">niratchadah@hotmail.com I do really appreciate.

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    #167998

    aiman farid
    Participant

    Hi everybody,
    May I see your excell file ?
    Thanks alot in advance.
    Aiman
    aiman_faridhotmail.com

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    #168000

    Mikel
    Member

    Why  you  want  to  do  that?

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    #168001

    Mikel
    Member

    Nothing would help you to understand it ,if you havn’t understood it
    in the past….   

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    #168002

    Fake ATI Alert
    Participant

    I want to apologize for all of the stupid questions I have asked
    over the years as Dog Sxxt, Marlon Brando, and all of the other stupid
    names I have used.I also am ashamed of myself for posting as Stan for the last week.

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    #168005

    Joe BB
    Participant

    You are not StanBoy. StanBoy would not say “Why you want to do that?”. He cannot write in English but he does speak English, you do not.

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    #168008

    Vadersback
    Member

    BC,
    Could you send me the File at @hotmail.com">veebhave@hotmail.com
    Regards
    Vadersback
     

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    #168553

    delli
    Participant

    I am also interested in it. kindly send the excel file to me if possible.
    My email: [email protected]
    Thanks & Regards,
    Delli

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    #168644

    Tierradentro
    Participant

    I would like a copy of your Excel file.
    email: [email protected]
     
    Thanks,
     
    John

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    #168656

    Stan”s sister
    Member

    Please send me a copy: [email protected]
    Thanks 

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    #169834

    Gutierrez
    Participant

    Can you please send me the file as well.
    Thanks!
    [email protected]

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    #171144

    nadi fadoua
    Participant

    Hi,
    Plz could u email me a copy of yr excel file.
    My email is @hotmail.co.ukThank">nadifadoua@hotmail.co.ukThank you.
    Fadoua

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    #171187

    Rags
    Participant

    Hi…would you please send me also [email protected]
     

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    #171201

    Engine Lady
    Participant

    BC:  Could I ask for a copy of your excel file demo on alpha beta risk?  my address is suzbs at yahoo dot com.
     
    thank you in advance
    Engine Lady

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    #171204

    BC
    Participant

    Engine Lady,
    I could not deliver to this email address.  Might be my server, but can you please check?

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    #171236

    lonesharke
    Participant

    This issues has just recently cropped up at our facility, may I review your excel file too?  Thank you!
    [email protected]

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    #171409

    Siho
    Member

    Could you also please send your Excel file to me? Thank you.
    @hotmail.com">analogmind@hotmail.com

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    #171499

    Alvarez
    Participant

    Please send me a copy: andoratanhotmail.com
    Best Regards,
    Andrew
     

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    #171500

    Helen
    Participant

    could you send to me a copy for the excel of Alpha Risk & Beta Risk, my mail [email protected]

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    #172101

    jeevan ram
    Participant

    please send alpha nad beta risk

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    #172108

    BC
    Participant

    please post your email

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    #174917

    Angelica Altamirano
    Participant

    Would you send me the excel file that exemplifies the alpha beta exercise please? I´m dealing with this concepts nowadays…thanks

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    #174918

    Angelica Altamirano
    Participant

    Please send me the excel that clarifies the alpha – beta concepts , i´m dealing with this trouble concepts.
     
    Thanks
     

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    #174924

    BC
    Participant

    Angelica,
    Please post your email address and I will send it to you.

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    #175002

    Ranjit
    Participant

    do u still have the excel demonstrating alpha, beta risk with sample size. plz mail at [email protected]

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    #175012

    varun gulati
    Member

    Hi,
    Please send me the excel file.
    My email address [email protected]
    Thanks in advance
    Regards,
    varun

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    #175220

    Kubal
    Participant

    Please send this useful information
    thanks in advance
     
    rajiv

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    #175238

    BC
    Participant

    Please post your email address.
    Thanks.

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    #176105

    ju pak
    Participant

    Please send me the file. thank you very much
    email: [email protected]
    ju

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    #176109

    Bob Rome
    Participant

    Please send a copy to me as well:
     
    [email protected]
     
    Thanks!

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    #176119

    MAC
    Participant

    Dear Rakesh,
    Here is my email address [email protected]
    Kindly send your demo example to me. Thks.
    Kind rgds
    Mac
     

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    #176139

    Hodgson
    Member

    Can you also send the excel to me? [email protected]
    I appreciate it.

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    #176993

    Joe J
    Participant

    BC, could you please send me a copy of your Excel file demonstrating the Alpha and Beta Risk?  My email is:
    [email protected]
    Much appreciated,
    Joe
     
     
     

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    #177044

    Nwajei
    Participant

    Hi BC,
    Could you please send me the excel file if possible? [email protected]
    Thanks and regards,
    Frank

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    #177463

    Anthony Orzechowski
    Participant

    Could you also send me a copy of this spreadsheet at [email protected]
     
    Thanks,
    Tony

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    #177468

    J
    Member

    I am interested in your excel file about alpha and beta.. Please email it to me  at
    [email protected]
    Thank you
     

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    #177789

    Dion
    Participant

    BC:  Could you send me a copy of your excel file demo on alpha beta risk?  my address is [email protected].
    thank you in advance
    Dion

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    #178161

    eshetu legesse
    Participant

    i would like to have thioretical concept of beta and alpha risk
    pls

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    #178185

    Andrew Kennett
    Participant

    BC,
    Would you also please send me the excell demonstration of alpha and beta risk
    [email protected]
     
    Thanks
     
    Andrew

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    #179160

    KC
    Participant

    Could you send me please your excel file about alpha, beta risks! my email – [email protected]
    Thank you in advance!

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    #179163

    Kulkarni
    Member

    can u pl send me too on [email protected]m

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    #181051

    walden
    Participant

    BC,
    Would you please send me a copy of this Excel file you were discussing.  I would really appreciate it.  My e-mail is:
    @hotmail.com">christian_aragon@hotmail.com
    Thanks,
    Chris

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    #181053

    Dennis Z
    Participant

    Please send me a copy [email protected]
    Thank you

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    #183569

    Andy Baker
    Participant

    I would like to have the file if you can still send it.  Thanks in advance.
    [email protected]

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    #183731

    revampedImage
    Participant

    I know this is old but if you still can send the excel macro it would be greatly appreciated. Please send it to sample [at] revampedImage [dot] com

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