Department of Statistics, Ankara University Faculty of Sciences, Ankara, TURKEY

Turkiye Klinikleri J Med Sci.

doi: 10.5336/medsci.2020-78094

ABSTRACT

Objective: We use the most frequently used growth functions in the literature for estimating Turkey's cumulative number of confirmed coronavirus disease-2019 (COVID-19) cases. We analyze Brody, Bertalanffy, Logistic, Generalized Logistic, Gompertz, Richards, Negative Exponential, Stevens, and Tanaka models for determining the appropriate model. Material and Methods: The number of cases of COVID-19 in Turkey between March 17, 2020 and July 12, 2020 in Turkey were included in the study. The data used in the study were obtained from Johns Hopkins University. We used the most frequently used nonlinear growth models in the literature for estimating Turkey's cumulative number of confirmed COVID-19 cases. Matlab software was used to estimate the parameters in the models studied. Nonlinear least squares regression function is used in Matlab software. Results: According to the estimation results the best fitting model is the Richards model in terms of both the Mean Squared Error and R2 (Coefficient of Determination). Conclusion: We recommend touse the Richards model in modeling the cumulative COVID-19 cases. For estimating the future cases, it will be appropriate to use the Richards model. In addition, estimates of the number of daily cases obtained from the Richards model are not compatible with the actual number of daily cases. This may occur because estimations on these growth models can sometimes lead to erroneous results.

Keywords: Turkey; COVID-19; pandemic; growth function