Re: Are the scores normally distributed?

Thank you for your replies.
About the large sample size, just for clarification, this is not a sample,
these are all the scores.
Should I do a random sampling?
Other approach I tried was to normalize the data using the following
approach:
x = x - 2*x
log_data = np.log(x)   # to transform scores into positive value to apply
the log function
The log_data was also found to be not normally distributed.

Le ven. 7 déc. 2018 à 22:05, <[email protected]> a écrit :

>
>
> On Fri, Dec 7, 2018 at 12:08 PM Paul Hobson <[email protected]> wrote:
>
>> I think you misunderstand the null hypothesis.
>>
>> The null hypothesis for this test is that the data are *not* normally
>> distributed.
>>
>
> That's not correct. The null hypothesis is the data come from a normal
> distribution.
>
> My guess is that because of the relatively large sample size, the power is
> quite large and the test detects relatively small deviation from normality.
>
> len(x)
> Out[8]: 1444
>
> stats.skewtest(x)
> Out[9]: SkewtestResult(statistic=1.79241121722139,
> pvalue=0.073067119279312559)
>
> stats.kurtosistest(x)
> Out[10]: KurtosistestResult(statistic=3.5348152259352097,
> pvalue=0.00040806039300234271)
>
> According the the two separate tests that are combined in the normal test,
> the data has heavier tails, larger kurtosis than the normal distribution.
>
> (Using kstest as distance measure, however, shows that the normal
> distribution matches the data better than a t distribution with smaller df.
> Note, pvalues for kstest don't apply because loc and scale are estimated.)
>
> Josef
>
>
>
>
>>
>> Since the p-value is your examples is 0.0003 (i.e., less than 0.001), you
>> can reject the null hypothesis, suggesting that your data are normally
>> distributed.
>> -Paul
>>
>> On Fri, Dec 7, 2018 at 8:54 AM Bakary N'tji Diallo <
>> [email protected]> wrote:
>>
>>> Dear all,
>>> Hope you are doing very well.
>>>
>>> I am trying to apply a statistical normalization which require the
>>> values to be normally distributed.
>>> I have prepared a short notebook with all details.
>>>
>>> https://nbviewer.jupyter.org/github/diallobakary4/bioinformatics/blob/master/Normatily_test.ipynb
>>>
>>> It will be great if someone can help me out.
>>>
>>> Thanks
>>> Best regards
>>> --
>>>
>>> Bakary N’tji DIALLO
>>>
>>> PhD Student (Bioinformatics) <http://linkedin.com/in/bakarydiallo>, Research
>>> Unit in Bioinformatics (RUBi) <https://rubi.ru.ac.za/>
>>>
>>> Mail: [email protected] |  Skype: diallobakary4
>>>
>>> Tel: +27798233845 | +223 74 56 57 22 | +223 97 39 77 14
>>>
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-- 

Bakary N’tji DIALLO

PhD Student (Bioinformatics) <http://linkedin.com/in/bakarydiallo>, Research
Unit in Bioinformatics (RUBi) <https://rubi.ru.ac.za/>

Mail: [email protected] |  Skype: diallobakary4

Tel: ​+27798233845 | +223 74 56 57 22 | +223 97 39 77 14

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