• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.676-681
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• 2008

The evaluation of the effluent water quality of sewage treatment plant is one of the most important factor in calculating total maximum daily loads (TMDLs). Current method to calculate 95% upper limit of effluent water quality of sewage treatment plant assuming normal distribution of data needs to be implemented in case of non-normal distribution. We have investigated the applicability of percentile ranking method as a non-parametric statistical analysis in case of non-normal distribution of data.

• Journal of the Korean Home Economics Association
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• v.36 no.1
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• pp.143-155
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• 1998

This study was conducted to compare dietary intake and quality obtained by food frequency questionnaire(FFQ) and 24-hour recall method among 1249 Korean adults living in rural area. The survey was conducted twice; first with 65-items FFQ by interview and then with 24-hour recall method two years later. Nutrients intake estimated from two dietary methods showed significant difference. For nutrients except fat and iron, average intake value estimated from the FFQ were significantly higher than that from the 24-hour recall method(p<0.001). Ranking of the subjects by nutrient intake levels obtained by two methods were significantly correlated, but correlation coefficients were low. Percentage of subjects in the lowest or in the highest quintile by 24-hour recalls who belong to the nearest two categories by FFQ ranged from 45% to 61%, while the percentage falling into the opposite category ranged from 7% to 15%. Subjects' percentile rank of nutrient intake by 24-hour recall correlated with their average rank of nutrient intake by FFQ. Information on food groups by two method were not comparable because of the limited number of food items in FFQ. For most nutrients, RDA% or NAR from FFQ were higher than those from 24-hour recall, but INQ from 24-hour recall were higher than those from FFQ. From the results, results of 24-hour recall method seems to be useful in classifying subjects according to their nutrient intake if sample size is large enough.