Affiliations: [a] Department of Statistics and Actuarial Science, School of Physical and Mathematical Sciences, University of Ghana, Legon, Accra, Ghana | [b] Department of Computer Science, Ashesi University, Unnecessary Berekuso, Accra, Eastern Region, Ghana | [c] Department of Political Science, College of Humanities, University of Ghana, Ghana
Correspondence:
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Corresponding author: Richard Minkah, Department of Statistics and Actuarial Science, School of Physical and Mathematical Sciences, University of Ghana, Box LG 115, Legon, Accra, Ghana. E-mail: rminkah@ug.edu.gh.
Abstract: This study focuses on the use of digits-based test in anomaly detection in presidential elections in Ghana. Even though Ghana has conducted several successful elections to elect presidents, the outcomes of the elections have been challenged in courts on allegations of vote rigging and fraud. It has been established in the literature that for an election to be anomaly free, the following should be satisfied: the distribution of voters turn-out, the winners’ share and total valid votes cast in the election should be uni-modal. Therefore, we assess the applicability of both first and second digits-based tests to aid in the detection of possible anomaly in the 2016 and 2020 presidential election results data in Ghana. The Benford frequency distribution and Spearman rank correlation coefficient tests were used for the analysis of data obtained from the Electoral Commission of Ghana. The results show that the observed first digits distributions of valid vote counts for both New Patriotic Party (NPP) and National Democratic Congress (NDC), and the total valid votes cast (TVVC), in 2016 and 2020 are consistent with the distributional pattern of first digits postulated by Benford’s Law. However, the findings of the distribution of second digits of the valid vote counts for NPP and total valid vote cast in both 2016 and 2020 elections do not satisfy the probability distributional pattern of second digits according to the Benford’s Law. In view of these, we recommend using the first two digits-based tests to check for consistency of possible election anomaly between the first and second digits since it conveys more information.
Keywords: Benford’s law, Spearman rank correlation coefficient, first digits, second digits, valid votes cast, Ghana
