tailieunhanh - Air Sampling and Industrial Hygiene Engineering - Chapter 4

Phân tích thống kê và phù hợp Chương này bao gồm các cuộc thảo luận lý thuyết và thực tế về phân tích thống kê. Nó đặc biệt nhấn mạnh với các tình huống nơi mà kiến thức liên quan thống kê là một điều kiện tiên quyết để lấy mẫu đầy đủ. Nó cũng minh họa sự khác biệt giữa phân phối đăng nhập bình thường và bình thường và dữ liệu giám sát tham số. Định nghĩa Trong phân tích thống kê và tính phù hợp, định nghĩa một số tiêu chuẩn được sử dụng. Các định nghĩa. | CHAPTER 4 Statistical Analysis and Relevance This chapter contains theoretical and real-world discussions about statistical analysis. It gives special emphasis to situations where knowledge of statistical relevance is a prerequisite for sampling adequacy. It also illustrates the difference between log-normal and normal distribution and parametric monitoring data. DEFINITIONS In statistical analysis and relevance certain standard definitions are used. The following standard definitions and examples illustrate the basic concepts. Accuracy Agreement of the measured value . empirical value and the true value . accepted reference value of the sample given valid sampling techniques proper sample preparation and reliable and accurate instrumentation and or other procedures. Accuracy is often estimated by adding or spiking known amounts of the target parameters. For asbestos quality assurance QA sampling accuracy is evaluated by comparing analyses of duplicate samples that have been evaluated in proficiency in analytical testing PAT round robins for air samples or NIST National Voluntary Laboratory Accreditation Program NVLAP proficiency testing for bulk and transmission electron microscopy TEM . Accuracy is a measure of the bias of the method and may be expressed as the difference between two values a ratio or the percentage difference. Analysis Combination of sample preparation and evaluation. Audit Systematic determination of the function or activity quality. Bias Systemic error either inherent in the method or caused by measurement system artifacts or idiosyncrasies. Blind sample Presented to the laboratory as indistinguishable from field samples syn performance audit samples . All field blanks are to be presented to the laboratory as blind samples for asbestos air samples. Calibration Comparative procedure in which singular measurements are evaluated against an accepted group of measurements. The evaluation may be against a primary intermediate or secondary