https://jbau.bau.edu.bd/index.php/home/issue/feed 2025-12-03T04:12:37+00:00 Executive Editor editor.jbau@bau.edu.bd Open Journal Systems <p>Journal of Bangladesh Agricultural University (JBAU) is an official publication of the <a href="http://baures.bau.edu.bd/">Bangladesh Agricultural University Research System (BAURES)</a>. JBAU publishes full-length original research and review articles from all areas of Agricultural Sciences and reflecting the considerable and continuing changes with particular emphasis on interdisciplinary studies from the researchers throughout the world. JBAU is a peer reviewed journal published quarterly (March, June, September and December) in a year. Electronic copies of the journal are available at <a href="http://jbau.bau.edu.bd" target="_blank" rel="noopener">http://jbau.bau.edu.bd</a><br /><br /></p> <div> <p><strong>Published by<br /></strong>Chief Editor<br />Director, Bangladesh Agricultural University Research System<br />Bangladesh Agricultural University (BAU), Mymensingh<br />Bangladesh</p> <p><strong>Correspondence<br /></strong>All sorts of correspondence to the journal have to be made directly to the Executive Editor or Managing Editor of Journal of the Bangladesh Agricultural University, Bangladesh Agricultural University Research System, BAU, Mymensingh, Bangladesh.</p> <p><strong>Telephone:</strong> +880-91-67401-6 Ext. 2037<br /><strong>Mobile:</strong> +88 01718 512 082/+88 01709 050 350<br /><strong>Fax:</strong> +88 091-67417<br /><br /><strong>E-mail:</strong><br />Executive Editor: <a href="mailto:associatedirector.baures@bau.edu.bd">associatedirector.baures@bau.edu.bd</a><br />Managing Editor: <a href="mailto:editor.jbau@bau.edu.bd">editor.jbau@bau.edu.bd</a></p> </div> https://jbau.bau.edu.bd/index.php/home/article/view/558 2025-12-03T04:12:37+00:00 Md Kamrul Hasan kamrulext@pstu.ac.bd Lalit Kumar kamrulext@pstu.ac.bd

<p>Determination of a valid sample size is a fundamental step in research. This paper explains how existing formulas are tied in a single thread by applying the concept of standard error, margin of error, Z and t scores, confidence interval and sampling distribution. Bringing the concept of sample control ratio, we suggest a unified formula which is n = (N t^2 ρ^2) / (N + t^2 ρ^2)​ where I is the sample size, N is the population, t is the t-value at a desired level of probability with df = (N-1) and ρ is the sample control ratio to be estimated by 1/(6ε) for continuous variables and √(p(1−p)/ε) for categorical variables where ε is the proportion of acceptable error and p is the proportion of presence of an attribute in the population. This formula does not need the finite population correction, and it has been derived from and consistent with existing formulas. A researcher does not need to calculate the error margin in absolute terms for this formula, and it is sufficient to provide only the proportion of error (e.g., 0.03 or 0.05). This paper should help social scientists, researchers, academicians and students determine the appropriate sample size for their research with greater confidence and clarity.</p>

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