Journal of Food, Agriculture and Environment

Vol 10, Issue 1,2012
Online ISSN: 1459-0263
Print ISSN: 1459-0255

Investigating impact of outliers in both independent and dependent variables on agricultural production data


Provash Kumar Karmokar 1, 3*, Mahendran Shitan 1, 2

Recieved Date: 2011-09-06, Accepted Date: 2012-01-04


The production of high yielding variety (HYV) Boro rice depends on both climatic variables and some other non-climatic variables. Outliers may occur commonly in agriculture data. Regression outliers either in independent variables or in dependent variables pose a serious threat to traditional least squares analysis. The impact of some climatic and non-climatic variables like temperature, rainfall, net solar radiation, humidity and wind speed, lag-price and fertilizer use on HYV Boro rice production have been investigated using regression diagnostics and robust regression techniques. In this study, we considered the annual HYV Boro rice production data from 1980 to 2000 for Mymensingh and Dinajpur districts in Bangladesh. We found that there were outliers in both the independent and dependent variables. The outlying observations that were found in the independent variables were corrected by the median of the respective variable series, the outliers in the dependent variables have been corrected by the robust least-trimmed squares (LTS) predicted observations of the HYV Boro production of the selected districts. Hence, the re-weighted least squares (RLS) estimation techniques have been used to judge the impact of outliers. The regression diagnostics for the selected districts were computed by both the OLS and RLS methods. Our study reveals that proper correction of outliers is very important for the regression models and there was improvement in the R- squared values for both the districts. 


Multiple regression, least square estimators, regression diagnostics, outlier, robust regression, high yielding variety (HYV), climatic and non-climatic variables

Journal: Journal of Food, Agriculture and Environment
Year: 2012
Volume: 10
Issue: 1
Category: Agriculture
Pages: 573-577

Full text for Subscribers

Note to users

The requested document is freely available only to subscribers/registered users with an online subscription to the Journal of Food, Agriculture & Environment. If you have set up a personal subscription to this title please enter your user name and password. All abstracts are available for free.

Article purchasing

If you like to purchase this specific document such as article, review or this journal issue, contact us. Specify the title of the article or review, issue, number, volume and date of the publication. Software and compilation, Science & Technology, all rights reserved. Your use of this website details or service is governed by terms of use. Authors are invited to check from time to time news or information.

Purchase this Article:   20 Purchase PDF Order Reprints for 15

Share this article :