As regards decreasing cotton cultivation in Iran during these years, the degree of risk taken by a cotton cultivator in the agricultural part is important. The studies showed that the cotton crop yield during the past years did not have enough growth and the cotton cost product in the period of study cotton production costs, has increased. In this paper, the risk orientation of cotton cultivato...

Mathematical modeling is a vast field that has interdisciplinary implications for research. These models help to investigate the basic dynamics and quantitative behavior of infectious diseases affect human beings, such as COVID-19, hepatitis B virus (HBV), immunodeficiency (HIV). The current study investigates spread HBV by using model. In order determine stability disease-free endemic equilibr...

In statistics, samples are drawn from a population in data-generating process (DGP). Standard errors measure the uncertainty sample estimates of parameters. science, evidence is generated to test hypotheses an evidence-generating (EGP). We claim that EGP variation across researchers adds uncertainty: non-standard errors. To study them, we let 164 teams six on same sample. find sizeable, par wit...