Programming the statistical procedures from SAS

doubt in understanding the code/procedure

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New Contributor
Posts: 3

doubt in understanding the code/procedure

[ Edited ]
Hello All,

I have a doubt in the below program, can anyone help me to find why they have used 0.5 while calculating logauc differecne, and also how to interpre the results

data bioequiv; input subject sequence $ AUC_T CMAX_T AUC_R CMAX_R; logAUC_T=log(AUC_T); logCMAX_T=log(CMAX_T); logAUC_R=log(AUC_R); logCMAX_R=log(CMAX_R); cards; 01 TR 4321.7 360.11 4415.3 278.48 02 RT 2139.5 326.19 8846.2 605.45 03 RT 8295.5 578.66 7399.1 608.67 04 TR 5974.9 412.69 3071.2 196.19 05 TR 5121.9 423.98 7513.4 681.34 06 TR 18750.4 1359.86 17096.2 1191.91 07 RT 5609.7 1046.37 4498.8 392.45 08 RT 9040.9 733.80 7847.2 571.51 09 TR 21120.1 2403.67 22603.2 1449.63 10 RT 4865.3 669.17 8127.3 738.77 11 RT 7244.6 717.01 6249.4 364.80 12 TR 5543.7 409.05 4915.3 468.31 13 RT 9748.2 907.64 12218.5 884.73 14 RT 10257.4 995.68 6021.4 557.16 15 TR 10996.2 2434.96 15284.0 2509.14 16 TR 8031.0 476.31 2495.1 265.09 17 TR 6527.5 565.66 14736.4 1070.06 18 RT 6385.5 579.72 5118.7 483.04 19 RT 4077.1 297.07 2068.3 123.90 20 TR 7088.0 1334.96 6363.2 1064.23 21 RT 10689.3 1702.07 36108.5 2552.32 22 RT 4615.1 656.33 4551.9 403.34 23 TR 3792.8 441.33 10444.7 2057.38 24 TR 9429.5 1458.82 21239.7 1899.42 25 TR 4272.4 500.45 7247.8 945.48 26 RT 9442.7 905.35 3872.8 247.49 27 RT 7373.2 688.03 5522.3 449.56 28 TR 1883.5 139.61 3299.3 213.63 ; run; ************************************************************************* * Construct the intra-subject differences (times one-half) within each * * sequence. Then perform the statistical analysis. * *************************************************************************; data diff; set bioequiv; if sequence='TR' then logAUC_diff=0.5*(logAUC_T-logAUC_R); if sequence='RT' then logAUC_diff=0.5*(logAUC_R-logAUC_T); if sequence='TR' then logCMAX_diff=0.5*(logCMAX_T-logCMAX_R); if sequence='RT' then logCMAX_diff=0.5*(logCMAX_R-logCMAX_T); run; proc ttest data=diff alpha=0.10; class sequence; var logAUC_diff logCMAX_diff; title2 'Parametric Analysis'; run;

Thanks
Super User
Posts: 10,812

Re: doubt in understanding the code/procedure

Who ever wrote the code provides exactly why they used 0.5.

*************************************************************************
* Construct the intra-subject differences (times one-half) within each  *
* sequence.  Then perform the statistical analysis.                     *
*************************************************************************;

Without any knowledge of the entire process or question asking for the original analysis I'm not sure I want to guess about the whole process or why half the difference was needed.

 

Respected Advisor
Posts: 2,655

Re: doubt in understanding the code/procedure

Square root of the ratio leads to half the difference on the log scale.  No clue why they want this, though.

 

Steve Denham

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