• Title/Summary/Keyword: Incomplete crossover design

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A Comparative Study of Assessing Average Bioequivalence in $2{\times}2$ Crossover Design with Missing Observations

  • Park, Sang-Gue;Choi, Ji-Yun
    • Journal of the Korean Data and Information Science Society
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    • v.17 no.1
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    • pp.245-257
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    • 2006
  • A modified Anderson and Hauck(1983) test for analyzing a two-sequence two-period crossover design in bioequivalence trials is proposed when some observations at the second period are missing. It is based on the maximum likelihood estimators of average bioequivalence model and designed for handling missing at random(MAR) situation. The performance of the proposed test is compared to other tests using Monte Carlo simulations.

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Statistical Analysis of Bioequivalence Study in $3{\times}2$ Crossover Design ($3{\times}2$ 교차설계법에서 생물학적 동등성 시험의 통계분석)

  • Park, Sang-Gue;Kim, Jeong-Il;Chae, Sung-San;Ko, Seoung-Gon;Oh, Hyun-Sook;Yang, Wan-Youn;Kim, Dong-Sup;Choi, Young-Wook
    • Journal of Pharmaceutical Investigation
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    • v.28 no.4
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    • pp.231-239
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    • 1998
  • A $3{\times}2$ crossover design is considered for the bioequivalence of two test formulations with a control. It could be considered as a better choice over $3{\times}3$ crossover design because of the cost and experimental duration. Oh et al.(1998) derived $3{\times}2$ crossover design and discussed its benefits over the typical crossover designs. We consider here the statistical models for $3{\times}2$ crossover design and show its statistical properties. The statistical procedures for the bioequivalence in $3{\times}2$ crossover design are shown through an example and the results are summarized by satisfying the 3 standards that proposed by the Korea Food and Drug Administration Guidelines for Bioequivalence.

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Assessment of Bioequivalence with Dropout Subjects in 3$\times$3 and 3$\times$2 Crossover Design

  • Ko, seoung-gon;Oh, Hyun-Sook
    • Journal of the Korean Statistical Society
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    • v.29 no.2
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    • pp.219-229
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    • 2000
  • Oh et al.(1999) 3$\times$2 crossover design for assessing bioequivalence when two new generic drug formulations and innovator are simultaneously considered. This design is not only more efficient than 3$\times$3 one, proposed by Lee et al.(1998), in practical sense, but also more ethical in medical sense. However, the general statistical methods are not directly applicable to both designs when subjects are dropped out in the experiment, even though it is always possible in bioavailability and bioequivalence studies because of some administrative and economic reasons. In this research we propose an inference to drug effects when subjects are dropped out in the planed-for 3$\times$3 and 3$\times$2 crossover experiments. An example is given for illustration.

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Statistical Interpretation of Bioequivalence in 2 × 2 Crossover Design with Missing Observations (2 × 2 교차설계에 의한 생물학적동등성시험에서 결측치가 있을 때의 통계적 해석 방법)

  • Park, Sang-Gue;Lee, Jae-Young;Choi, Sung-Up;Yoon, Mi-Kyeong;Lee, Jae-Whi;Choi, Young-Wook
    • Journal of Pharmaceutical Investigation
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    • v.34 no.5
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    • pp.379-383
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    • 2004
  • Statistical interpretations in a bioequivalence trial are considered and studied when the missing observations occurred in $2\;{\times}\;2$ crossover experiment. Patel (1985) suggested the approximate test procedures for carryover effect and drug effect in $2\;{\times}\;2$ crossover design when some of data are missing in the second period. A modified Patel method is newly proposed to the bioequivalence trial and it is compared with the current method through the simulation study.

Nutrient Value of Saltwort (Salicornia herbacea L.) as Feed for Ruminants

  • Ishikawa, N.;Shimizu, K.;Koizumi, T.;Shimizu, T.;Enishi, O.
    • Asian-Australasian Journal of Animal Sciences
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    • v.15 no.7
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    • pp.998-1001
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    • 2002
  • Saltwort (Salicornia herbacea L.), a kind of halophytes in Japan, is under investigation as a feed source for livestock as well as potential oilseed crop in salt marshes and salt fields. The present experiment was undertaken to analyze the nutritive value of saltwort as feed for ruminants. To determine the apparent digestibility and nutritive value of saltwort, five Japanese native goats were fed the diets consisting of alfalfa hay cubes with 15 or 20% (n=3 and n=2, respectively) inclusion levels of saltwort in the total diet on a DM basis. All the animals were randomly offered alfalfa hay cubes as a base diet or a mixed diet of alfalfa hay cubes and saltwort at maintenance level, thereafter, alternative feed (a base or mixed diet) was offered to the experimental animals (the incomplete crossover design). Analysis of the chemical composition of saltwort showed that the plant contained high levels of total ash (40.2% DM), sodium (12.7% DM) and chlorine (19.7% DM), and relatively high levels of CP (11.7% DM) and NDF (40.4% DM). Contents of TDN and digestible CP (DCP), DE and ME of saltwort were 33.5% DM, 8.4% DM, 7.4MJ/DM kg and 5.0MJ/DM kg, respectively. These results indicate that saltwort is rich in DCP and minerals (mainly sodium chloride), but poor in energy, suggesting that saltwort could be used as a mineral or CP supplement for ruminants raised around salinized areas in which high quality feed may not be available.