Sample Size and Pearson’s Correlation on the Characteristics of the Crambe and Sunflower Plants

Aims: Determine the sample size and the Pearson correlation between the characteristics of the crambe and sunflower plants.

Study Design: Samples were collected from 108 crambe and sunflower plants.

Place and Duration of Study: The research was carried out at the Federal Rural University of Amazonia from November 2014 to February 2015.

Methodology: The data for 108 plants was subjected to a descriptive analysis of each variable and, subsequently, the sample size was estimated (η), with a mid-range of the confidence intervals of 1%, 5%, 10%, 15%, and 20% of the average (m) and a 95% coefficient of confidence. The sample size was obtained through the expression tα/2 , which it is the critical value of the Student t distribution, whose area, on the right, is the same as α/2, thus, the value of t, such that P[t>tα/2]=α/2, with (n-1) degrees of freedom, with (α>5%)of margin of error, and s2 is the variance estimate.

Results: The analyzed data displayed relatively high coefficients of variation for some parameters, while the number of grains of the lower raceme and the number of grains of the higher raceme demonstrated superior dispersal data for the crambe. For the sunflower, the number of seeds by section, and the mass of the section with and without seeds displayed high variability, and consequently, higher sampling demand numbers. Supplementary relevant points were that there were strong correlations between the mass of the section without seeds as opposed to the mass of the section with seeds.

Conclusion: Of the characteristics of the crambe and sunflower plants that were observed, the sample sizes required are larger than the ones analyzed here in order to properly estimate the parameters and Pearson’s linear correlation coefficient.