VARYASYON KATSAYISININ BAZI ÖZELLİKLERİ VE TÜRKİYE ZİRAİ ARAŞTIRMA KURUMLARINDA YAPILAN DENEMELERE UYGULANIŞI

Authors : Necati YILDIZ

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Publication Date : 2010-12-27

Article Type : Other Papers

Abstract :ÖZET Benzer muamdede ve materyal ile yapltan deneme~ lerden hesaplanan varya~yon katsayıarı belirli bir ortalama etrafında toplanırlar. Buna göre, Türkiye şartlanda çeşitli bitkilerle ilgili ortalama varyasyon katsayısı ve güven sınırları bilindiği taktirde, yapılacak denemelerin varyasyon katsayıları bu değerlerle karşılaştırılarak denemenin doğruluk derecesi hakkında bir hükme varılabilir. Bu hükümde denemenin etkinlik değeri de yardımcı bir kriter olarak kullanılmalıdır. , Bu çalışmada, Zirai Araştırma Kurumlarında uygulanmakta olan deneme planlarının doğruluk derecelerinin nasıl ölçülebileceği araştırılmıştır. Ayrıca" denemelerde hassasiyetin artırılmasına tesir eden faktörler ilebunların tayininde kullanılan metodlar da incelenmiştir. Elde edilen sonuçların anlaşılabilmesi ve uygulamayla ilgilerinin iyi kurulabilmesi için varyasyon kat· sayısının frekans dağılışı ve güven sınırları gibi teorik özelliklerine de yer verilmiştir. SUMMARY SOME PROPORTlES OF COEFFICIENT OF VARIATION AND APPLICATINON ON THE EXPERIMENTS CARRIEO OUT BY TURKISH AGRICULTURAL RESEARCH CENTERS. The purpose of this study was to tedermine the comparative sensitivity of the maıor experimental designs applied at the Agrieu!tural Experiment Statiorl$ in 1urkey. Some factors effecting the accuraey of the -experiments' and methods used to identifty these factors wereconsidered. As a qui.de for planning the next experiments confidence interva/, s of variation coefficients of de· signs and eertain treatment gro· ups are obtained· For thE'se proce~ dures the probability distriqution of the coeffieient of variatin must be known. Approximate distr.ibutions have been deva·loped by McKay (1932) and Hald (1951) among which the former's seems tu be more eonvanient. The eXact sampling distribution ware also obtained by Iglewicz (1967). Data used here, ir'ı this study i were colleeted from various Agri· cultural Experime:ı-ts as publishedresults of tre experiments performed since1960. Contidenee limits of the coefficionts of variation we· re estimated and' the best estimates were obtained uSilıg the nor.mal distr.ibution, Jakcnife tecnıque McKay's and Hald's appro· ximations. Coeffieients of va! i,ation and their confidenee intervals found for different experiments conducted with different crops and fertİlizers are shown in the following table. ---.-..,._-- -------_.._-- v (%) Confidence interva! (% 99) Wheat Barley Com Gotton Oat Wheat fertilizıng Cotton fertilizing The eoeffıcıent of var,j'ation of the experiment conlucted with a cartain crop palenı must stay, for the sake of sentivity, under the upper limit found with the precission experiments. For example, if 15,04 1231 < V < 19.59 14,72 9.28 < V < 20.16 18,13 13.92 < V < 22,41 9.45 6,61 < V < 13,46 20,98 12,79 < V < 2\3,89 19,03 14,31 < V < 27,77 15,22 11,86 < V < 18,62 ---_._----._. we should and up with an estimation more than 20 % of the coeffici. ent of variation we would lake our chooce of plan'ing of experiment quite a less sensitive one. 165 in the experiments conducted with different crops and fertilizers we tried to compare two methods of estirnatian of the number of replicates, namely, the method developed by Cochr~r;ı and Cox and that 'by Harris-Horvitz-Mood. Both of the methods gave the results with almost equal preciseness, but conside1ing the eace usability we would sugge~t to use the method of Cochran and' Cox prefarably. Accordingly we found the numbers of re~licat€s to test 25 % of the treatment means differences with a level of 20 % type ii error for the e>:periments with wheat, barley corn, cctton, aat crops and wheat and cotton fertilizıng 5, 7, 3, 8, 7, 5, respectively.
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