Programming the statistical procedures from SAS

Parametric / non-parametric ?

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Contributor
Posts: 34

Parametric / non-parametric ?

Actual 1100 1300 1400 1500 1600 1100 1200 1600 2100 1300 1600 1300 1600 2200 2300 1700 1800 800 1400 900 2100 1400 1800 1900 1000 1800 1700 2100 800 1100 900 1600 1700 1400 1100 1200 1700 900 700 900 1300 700 1500 700 1300 1100 1700 1600 1800 2000 1500 2100

Demand 1500 2100 1600 1500 2000 1600 1200 2000 2200 2000 2200 2000 2000 2500 2500 2000 2000 1000 2000 1500 2500 1500 2500 2500 2000 2000 2500 2500 1500 1500 1400 2000 2000 2000 1500 1500 2500 1500 1500 1500 2500 1500 2000 1500 1500 2000 2000 2500 2500 2500 2500 2500

These are the data collected. Both are sequential from 1st - 52nd weeks. How do determine whether it is parametric or non-parametric?

Trusted Advisor
Posts: 1,222

Re: Parametric / non-parametric ?

Try Kolmogorov Smirnov test for this.

Contributor
Posts: 34

Re: Parametric / non-parametric ?

The maximum difference between the cumulative distributions, D, is: 0.5000 with a corresponding P of: 0.000


Data Set 1:

52 data points were entered

Mean = 1440.

95% confidence interval for actual Mean: 1322. thru 1559.

Standard Deviation = 425.

High = 2.300E+03 Low = 700.

Third Quartile = 1.700E+03 First Quartile = 1.100E+03

Median = 1450.

Average Absolute Deviation from Median = 352.

KS finds the data is consistent with a normal distribution: P= 0.84 where the normal distribution has mean= 1449. and sdev= 422.6

KS is not particularly happy calling this data log normally distributed: P= 0.17 where the log normal distribution has geometric mean= 1332. and multiplicative sdev= 1.394

Items in Data Set 1:

700. 700. 700. 800. 800. 900. 900. 900. 900. 1.000E+03 1.100E+03 1.100E+03 1.100E+03 1.100E+03 1.100E+03 1.200E+03 1.200E+03 1.300E+03 1.300E+03 1.300E+03 1.300E+03 1.300E+03 1.400E+03 1.400E+03 1.400E+03 1.400E+03 1.500E+03 1.500E+03 1.500E+03 1.600E+03 1.600E+03 1.600E+03 1.600E+03 1.600E+03 1.600E+03 1.700E+03 1.700E+03 1.700E+03 1.700E+03 1.700E+03 1.800E+03 1.800E+03 1.800E+03 1.800E+03 1.900E+03 2.000E+03 2.100E+03 2.100E+03 2.100E+03 2.100E+03 2.200E+03 2.300E+03

Data Set 2:

52 data points were entered

Mean = 1948.

95% confidence interval for actual Mean: 1829. thru 2067.

Standard Deviation = 426.

High = 2.500E+03 Low = 1.000E+03

Third Quartile = 2.500E+03 First Quartile = 1.500E+03

Median = 2000.

Average Absolute Deviation from Median = 340.

KS says it's unlikely this data is normally distributed: P= 0.02 where the normal distribution has mean= 1923. and sdev= 419.7

KS says it's unlikely this data is log normally distributed: P= 0.00 where the log normal distribution has geometric mean= 1851. and multiplicative sdev= 1.288

Items in Data Set 2:

1.000E+03 1.200E+03 1.400E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.500E+03 1.600E+03 1.600E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.000E+03 2.100E+03 2.200E+03 2.200E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03 2.500E+03

Data Reference: 2786

KS finds the data is consistent with a normal distribution: P= 0.84 where the normal distribution has mean= 1449. and sdev= 422.6

KS is not particularly happy calling this data log normally distributed: P= 0.17 where the log normal distribution has geometric mean= 1332.  <---- what do these 2 sentences mean?

Trusted Advisor
Posts: 1,222

Re: Parametric / non-parametric ?

Seems like data2 variable does not follow normal distribution.

Contributor
Posts: 34

Re: Parametric / non-parametric ?

so my data1 is following normal distribution and data2 is not.... therefore which test should i use and what assumption should i make ?

Trusted Advisor
Posts: 1,222

Re: Parametric / non-parametric ?

Why do you want to compare two variables which are not following same distribution?

Contributor
Posts: 34

Re: Parametric / non-parametric ?

I have to prove that in order to justify the problem in my project. If these 2 variables are not following same distribution,is that any way to compare them?

Trusted Advisor
Posts: 1,222

Re: Parametric / non-parametric ?

Your data2 variable does not seem a random variable, it contains values which are very similar to each other. It is evident that two variables are different.

Contributor
Posts: 34

Re: Parametric / non-parametric ?

in case of that, what test should I use in order to prove the significant difference in these 2 data?

Trusted Advisor
Posts: 1,222

Re: Parametric / non-parametric ?

Okay, I would say just divide data points of two variables into 4 to 5 classes and run chi-square test to see if there is an association between two variables.

Contributor
Posts: 34

Re: Parametric / non-parametric ?

what will be my hypothesis in chi square test?

Trusted Advisor
Posts: 1,222

Re: Parametric / non-parametric ?

Is there any association between two classifications?

Contributor
Posts: 34

Re: Parametric / non-parametric ?

Ok. Thanks a lot... I will proceed with that later...

If I proved that the 2 variables are independent , what test should I use then?

how about I prove they are dependent ?

Trusted Advisor
Posts: 1,222

Re: Parametric / non-parametric ?

Please try then we can go from there.

Contributor
Posts: 34

Re: Parametric / non-parametric ?

Chi-Square Test for Association: Worksheet rows, Worksheet columns

Rows: Worksheet rows   Columns: Worksheet columns

       600-1000  1100-1500  1600-2000  2100-2600  All

1            10         19         17          6   52

           5.50      17.50      17.50      11.50

2             1         16         18         17   52

           5.50      17.50      17.50      11.50

All          11         35         35         23  104

Cell Contents:      Count

                    Expected count

Pearson Chi-Square = 12.910, DF = 3, P-Value = 0.005

Likelihood Ratio Chi-Square = 14.316, DF = 3, P-Value = 0.003

here is the result that i obtained from minitab

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