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Wyszukujesz frazę "Akpan, E. A." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Application out-of-sample forecasting in model selection on Nigeria exchange rate
Autorzy:
Henry, Akpensuen Shiaondo
Lasisi, K. E.
Akpan, E. A.
Gwani, A. A.
Powiązania:
https://bibliotekanauki.pl/articles/1062858.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
ARMA model
Exchange Rate
In-sample forecasting
Model selection and evaluation
Out-sample forecasting
Opis:
In time series, several competing models may adequately fit a given set of data. At times choosing the best model may be easy or difficult. However, there are two major model selection criteria; it could be either in-sample or out-of-sample forecasts. This study was necessitated because Empirical evidence based on out-of-sample model forecast performance is generally considered more trustworthy than evidence based on in-sample model performance which can be more sensitive to outliers and data mining. And also the fact that Out-of-sample forecasts also better reflect the information available to the forecaster in real time was also an added motivation. Hence this study considered data from Nigeria exchange rate (Naira to US Dollar) from January 2002 to December 2018 comprising 204 observations. The first 192 observations were used for model identification and estimation while the remaining 12 observations were holdout for forecast validation. Three ARIMA models; ARIMA (0, 1, 1), ARIMA (1, 1, 2) and ARIMA (2, 1, 0) were fitted tentatively. Base on in-sample information criteria ARIMA (0, 1, 1) was the best model with minimum AIC, SIC and HQ information criteria. However, on the basics of out-of-sample forecast evaluation using RMSE, MSE, MAE, and MAPE, ARIMA (2, 1, 0) perform better than ARIMA (0, 1, 1). The implication of this study is that, a model that is best in the in-sample fitting may not necessary give a genuine forecasts since it is the same data that is used in model identification and estimation that is also use in forecast evaluation.
Źródło:
World Scientific News; 2019, 127, 3; 225-247
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In vitro control of tomato (Solanum lycopersicon L.) fruit rot caused by fungi using two plant extracts
Autorzy:
Okey, E.N.
Akwaji, P.I.
Akpan, J.B.
Umana, E.J.
Bassey, G.A.
Powiązania:
https://bibliotekanauki.pl/articles/11144.pdf
Data publikacji:
2016
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Opis:
The inhibitory properties of the ethanolic and methanolic leaf extracts of Vernonia amygdalina and Cola acuminata on the fungal pathogens isolated from infected tomato fruits were investigated. The pathogens were Fusarium moniliformes and Rhizopus stolonifer. Various concentrations of the extracts ranging from 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100% were separately added to PDA media. The fungal pathogens were separately inoculated into the media and incubated for seven days. Antifungal effects of these extracts on the mycelia growth of the pathogens were significant at P<0.05 for all treatments at higher concentrations. At 10-50% concentration, ethanolic and methanolic extracts of Vernonia amygdalina and Cola acuminata had no significant effect on the mycelia growth of Fusarium moniliformes and Rhizopus stolonifer after seven days observation period. At 60-100% concentrations, the two pathogens were completely inhibited by ethanolic extracts of Vernonia amygdalina and Cola acuminata. Methanolic extracts of Vernonia amygdalina and Cola acuminata inhibited completely Fusarium moniliformes and Rhizopus stolonifer at 80-100% concentrations. The in vitro inhibitory effects of these extracts at higher concentrations indicated that they can be used for the control of tomato fruit rot. It may be necessary to use them in prolonging the shelf-life of fresh tomato fruit and some other fruits.
Źródło:
International Letters of Natural Sciences; 2016, 52
2300-9675
Pojawia się w:
International Letters of Natural Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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