A Principal Component Analysis of Auchi Region, Edo State
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FUTY Journal of the Environment Vol. 10 No. 1 November, 2016 Dimensioning Environmental Indicators: A Principal Component Analysis of Auchi Region, Edo State *aOnaiwu, D. N. bOnaiwu, F. O. aDepartment of Geography and Regional Planning, Faculty of Social Sciences, University of Benin, P.M.B 1154, Benin City bDepartment of Building Technology, School of Environmental Studies, Auchi Polytechnic, P.M.B 13, Auchi, Edo State *correspondence e-mail: [email protected] Abstract The environment is a multidimensional system and its components are interrelated and fuzzy. The environment is of concern to humans because of its growing deterioration which has prompted the need to improve its quality. Hence environmental quality assessment has become a means of determining quality. The study is on dimensioning the 66 variables that affect the quality of Auchi Region. Principal component Analysis was used to select the underlying factor structure of the variables. The result is an 8-factor solution of housing, erosion, distance, solid waste, natural environment, flooding, land use and erosion effects that explain 46.26 per cent of the variance in environmental quality of Auchi Region. The technique is recommended as an effective means of dimensioning the complex system of environment in less developed countries where data input is difficult to obtain. Keywords: Environmental Indicators, Principal Components, Dimensionality, Auchi INTRODUCTION Environment has become a major focus of research in the 21st century because of increasing problems affecting humans. The environment is multidimensional and it is not easily amenable to a comprehensive handling (Adriaanse, 1993; Bartone, Bemstein, Leitmann & Eigon 1994). Many researchers have approached it narrowly from their own disciplinary background. However the environment is a great container and a web of interrelationships. These relationships must be accounted for, if any meaningful investigation of the environment is to be embarked upon. Many phenomena in the habitat of man do have environmental implications and impacts. These underscore the need for us to be interested in environmental concerns. The starting point of the study of environment is what to distil as the constituents of environment. The environment is multidimensional as approached by many scholars taking toll on the air, water, and ground quality, pollution, biosphere and the cultural elements and built developments (Cunningham and Saigo, 2001; Khatun, 2007). The intricate nature of the environment is such that the seemingly endless list of elements does not exist in isolated bits, but rather are closely knitted together in a web. The complex nature of the environment has fostered researchers to seek interest in modelling environmental components in the form of indicators. These indicators are hung on themes like water, air, biotic, economic development and built environment. These indicators are, however, not comprehensive and scientific enough to capture the essence of the environment they are modelling. After the Rio Earth Conference Brazil, various international organisations, national governments, and institutions have evolved different environmental quality indicators to study the environment (Chang- ching, Quinn, Dufournould, Harrington, Rogers and Lohani 1998). One theme that runs through the indicators derived by the United Nations Environmental Programme (UNEP), World Bank and Dutch Government (Chang-Ching et al, 1998) is that the indicators have been hampered by the complexity of the environment system regarding what to measure and how to measure them. Since the environment is multidimensional and complex, dimensioning it requires simplification and data reduction. A good statistical technique of achieving this is principal component analysis (PCA). The present study aims 52 FUTY Journal of the Environment Vol. 10 No. 1 November, 2016 at dimensioning the indicators of the environmental quality of Auchi Region in Edo State. The theoretical search started with the review of literature on the built environment of a region. Sixty-six variables that described the environment of Auchi Region were chosen for the purpose and these are pretty too many and fuzzy for dimensioning the environment of Auchi Region. The study sought to reduce these sixty-six variables into a few dimensions that can indicate the quality of environment of Auchi Region. Thus, the study will answer these questions: How many variables can be used to dimension the quality of Auchi Region? How is principal component analysis used to dimension the environmental quality of Auchi Region? It is hoped that these would help policy makers to reach decisions on environment measurement. The Study Area The location for the investigation is Auchi Region. Taking Auchi as the locus, and a radius of about 10.5km, the area spans about 346.361km2. The area has western boundary with Owan East and Akoko-Edo LGAs, an eastern boundary with Etsako Central and in the southern area it is bounded by Esan West, Esan Central and Esan North-east. The area has some few urban centres in Auchi and Jattu. Ughiole, South- Ibie and Jattu are coalescing with Auchi to form one continuous urban form. Methodology The concept of environmental quality is multidimensional and has been carried out by many assessors using different approaches. In this study interview survey was used in recording the responses of participants because it afforded the opportunity of trained interviewers to clarify some issues to the respondents. The following steps were followed: Sampling The study area is the Auchi Region. Although the Town Planning Authorities use a radius of 5.5 km from a point in Warrake Road, Auchi as its declared planning area based on schedule iv of the defunct Bendel State of Nigeria Gazette No. 67 vol. 26 of December 1989, this application is inadequate for this study. Reason being that commuting distance covered in terms of interaction between residents of Auchi and its neighbours far exceeds this. A distance of 10.5 kilometres was chosen based on the commuting distance covered by workers of Auchi Polytechnic, Auchi from their residences. From available estimates based on the National Population Censuses of 1991 and 2006 and the arithmetic projection carried out to 2011 the population of the region is 232, 126 persons. However, the study population is based on the population of the 24 sampled settlements which is 216,468 persons. A sampling fraction of 0.005 was used to determine the sample size for the survey. This gives a sample size of 1082 respondents. A sample size calculator gives 384 as the precise sample size for a population of 216,468 at an accuracy of error margin of 5 per cent and at 95 per cent confidence level (Van Ambury cited in Mitchell & Jolley, 2007. This is far less than the chosen sample size of 1082 persons. The study population was chosen based on the spatial distribution of population among the settlements and the PCA technique as applied in the study. There are 38 settlements within the radius of 10.5 Km that form Auchi Region. These settlements are the large population centres of Auchi, Jattu, Iyakpi and 35 villages. The three urban nodes are of relatively large population concentrations compared to other settlements in the region. The disparity in the size of population between the large and the small settlements necessitated the splitting of the three large settlements for comparability of their sizes (see Table 1). Auchi was split into six units (Igbei, Akpekpe, Aibotse, Usogun, Iyekhei and GRA); Jattu into two (Old and New); and Iyakpi into two (Old and New). Thus Auchi, Jattu and Iyakpi were divided into ten spatial units. The following settlements were combined into seven pairs (Ikabigo/Idato, Ibienafe/Ugieda, Iyerekhu/Ughiekhai, Ayua/Elele, Buneka/Ebese, Afashio/Afowa and Uluoke/Ogbido. The pairing is based on their contiguity. The remaining eight settlements, each on its own, stood as a spatial unit. Altogether there are 24 spatial sampling units that were used for the survey. 53 FUTY Journal of the Environment Vol. 10 No. 1 November, 2016 Figure 1: A sketch of Auchi, the study area. The distribution of the sampled respondents for the interview survey is shown in Table 1. The survey carried out in the region shows a response rate of 81.89 per cent (i.e. 886 respondents were interviewed across the 24 spatial sampling units). The distribution of those interviewed in the 24 spatial sampling units is shown in Table1. The respondents for the survey were the heads of households. A household is regarded as persons that live together, eat together and share the same apartment. The selection of the respondents was based on a random systematic sampling. In the larger sampling units, a household head was interviewed at every 5th house from randomly selected streets; and in the smaller sampling units an interval of every 2nd house was used. Wherever these requirements were not met in the smaller sampling units, any available household head was interviewed in a house. 54 FUTY Journal of the Environment Vol. 10 No. 1 November, 2016 Table 1 Sample units of the study area Zone Settlement/Quarters Population Size Sample Size Initial Administered Auchi – A 1. Igbei 9,240 46.2 39 Urban core 2. Aibotse 12,320 61.5 57 3. Usogun 21,560 107 81 4. Akpekpe 18,480 92 81 5. Iyekhe 15,400 77 61 6. GRA 6,161 30 25 83,161 Intermediate – B 7. Jattu (1-Old) 16,725 83 65 8. Jattu (11 – New) 11,151 56 42 9. Afashio/Afowa 8,384 42 34 10. Ikabigbo/Idato 4,602 23 20 11. Ibienafe/ugieda 5,184 26 31 12. Ayua/Elele 6,735 34 29 13. Ugioli 5,791 29 25 14. Iyakpi (1 – Old) 5,984 30 26 15. Iyakpi (11 – New) 7,978 40 28 72,534 Periphery – C 16. Iyuku 7,568 38.8 42 17. Iyerekhu/Ughiekhai 3,978 20 19 18.