tailieunhanh - Statistics for Environmental Science and Management - Chapter 9

Cũng giống như phân tích chuỗi thời gian, phân tích dữ liệu không gian là một lĩnh vực chuyên môn cao trong thống kê. Vì vậy, tất cả những gì có thể trong chương này là để minh họa cho các loại dữ liệu có liên quan đến, mô tả một số trong những phương pháp đơn giản của phân tích và cung cấp cho các tài liệu tham khảo để biết thêm thông tin có thể được lấy. | CHAPTER 9 Spatial Data Analysis Introduction Like time series analysis spatial data analysis is a highly specialized area in statistics. Therefore all that is possible in this chapter is to illustrate the types of data that are involved describe some of the simpler methods of analysis and give references for where more information can be obtained. The methods of analysis that are considered in this chapter can be used to a detect patterns in the locations of objects in space b quantify correlations between the spatial locations for two types of objects c measure the spatial autocorrelation for the values of a variable measured over space and d study the correlation between two variables measured over space when one or both of those variables displays autocorrelation. To begin with some example sets of data are presented to clarify what exactly a to d involve. Types of Spatial Data One important category of spatial data is quadrat counts. With such data the area of interest is divided into many square rectangular or circular study plots and the number of objects of interest is counted in either all of the study plots or a sample of them. Table gives an example. In this case the study area is part of a beach near Auckland New Zealand the quadrats are circular plots in the sand with an area of and the counts are the numbers of two species of shellfish pipis Paphies australis and cockles Austrovenusstutchburyi found down to a depth of in the quadrats. These data are a small part 2001 by Chapman Hall CRC of a larger set obtained from a survey to estimate the size of the populations with some simplification for this example. Table Counts of two species of shellfish from quadrats in an area 200m long by 70m wide of a beach in Auckland New Zealand. The position of the counts in the table matches the position in the study area for both species so that the corresponding counts for the two species are from the same quadrat Distance from Distance .