Contents Page 1 of 5 Print A Statistical Quality Management Framework for Sample Surveys in an Official Statistical Agency Sessions STCPMs Marlize Pistorius; Luthando Mayekiso Statistics South Africa. De Bruyn Park Building, 170 Andries Street, Pretoria 0002, South Africa. E-mail: [email protected]; [email protected] Statistics can be seen to be produced by a Statistical value chain (SVC). The most general or complete form of the SVC can be seen as that which emanated from the Joint UNECE/Eurostat/OECD Work session on Statistical metadata [1], which is called the Generic Statistical Business Process Model (GSBPM). The GSBPM is composed of ten high level business activities, namely, specify needs, design, build, collect, process, analyse, disseminate, archive, evaluate, and a quality management or metadata management. Each of these high level activities can be further decomposed into lower level activities, usually composed of three to nine sequential sub-activities. The sub-activities and any further decomposition of these activities have an impact in the final statistical quality of the estimate that emanates from the process. T Contents Page 2 of 5 Print The statistical quality can be measured using a statistical quality assessment framework. In the South African setting such a framework is called the South African Statistical Quality Assessment Framework (SASQAF), and is composed of nine dimensions, namely, pre-requisites of quality, relevance, accuracy, timeliness, accessibility, interpretability, coherence (and comparability), methodological soundness and integrity. Another example is the Eurostat quality indicators [2], which is more suitable for the Euro region setting, but Sessions STCPMs can be adapted to other settings. The Eurostat quality indicators have the advantage of being more quantitative in nature, and are thus more amenable to mathematical optimization. An optimal method to depicting and analyzing business processes is the Business Process Modeling Notation (BPMN) 1 and the IDEF0 2 diagrams. In Business Process Modeling Notation (BPMN) one has activities, flow arrows, events and gateways. The activity describes a work function performed by the process. The activity can be a sub-process which is a compound process that can be further collapsed into component activities. A flow is an icon used to show the order in which activities in the process take place, and an event is an occurrence in the environment of the process. A gateway is used to control the joining or separation of flows in the process. The IDEF0 diagram is comprised of a hierarchical set of diagrams, namely, a context diagram (A-0), a top-level diagram (A0), a decomposition diagram, a node diagram, and a for exposition T 1 Business Process management initiative, www.bpmi.org 2 Institute of Electrical and Electronic Engineers (IEEE) Std 1320.1-1998 (R2004) Contents Page 3 of 5 Print only (FEO) diagram. The modeling notations allow one to depict the business process using software such a Telelogic System Architect, iGrafx FlowCharter, WorkFlow Analyzer, AI0win, iGrafx IDEF0, ARIS, and Visio. The methods of Business Processes Redesign build on Business Process mapping concepts in order to Sessions STCPMs improve or increase the value added of the business process as defined by desired outcome. In the context of a Statistical Quality Management Framework within an Official Statistical Organization, one can make the simplifying assumption that better outcomes or better quality decisions will emanate from decisions made from better quality statistics. This then allows one to use the quality management framework to define real value adding activities, business-value-added, and non-value adding activities or alternatively loss functions, which are expenditures on the value chain that do not improve the statistical quality. In Business Process Redesign one wants to redesign in an innovative manner key business processes to achieve breakthrough improvements in business performance. Generally this involves improving activities, restructuring and reconfiguring process flows, changing information flows around processes, changing knowledge management around processes and configuring roles around processes. T In a Bayesian decision theory framework one can use the Statistical Quality Assessment framework to define Contents Page 4 of 5 Print statistical value. This can be used to define a loss function or a utility function. In this framework we let θ={θ1, θ2} be the state of nature about the quality improvement of a particular action. Then one can, using techniques outlined in [3], let A={a1, a2} represent two expenditure actions of equal size from fixed budget of resources. Assuming no data is available one can let π(θ) represent the probability distribution of θ and define an Expected Bayesian loss of each action ai, i=1 or 2, as ρ(π, ai)=Eπ L(θ, ai)=∫Θ L(θ, ai)f(x| θ)dθ. Then Sessions STCPMs using the Conditional Bayes Principle, one can choose the action ai, i=1 or 2, that minimizes ρ(π*, ai), where π(θ) is the prior distribution of θ, and π*(θ) is the posterior distribution of θ. The South African Quarterly Labour Force Survey was re-engineered according to actions outlined in [4] the standard error of the overall official unemployment estimate in September 2008 according to the Quarterly Labour Force Survey standard error was 74 196 while in September 2007 it was 115 306 (not taking into account other changes). REFERENCES ) [1] T Joint UNECE/Eurostat/OECD Work Session on Statistical Metadata (METIS) (2008), Generic Statistical Business Process Model. Contents Page 5 of 5 Sessions STCPMs Print T [2] Quality in Statistics (2005), Seventh Meeting, Eurostat, Doc.ESTAT/02/quality/2005/9/quality indicators. [3] J. Berger (1985), Statistical decision Theory and Bayesian Analysis, Springer-Verlag. [4] Statistics South Africa (2008), Report on the response by Statistics South Africa to recommendations of the International Monetary Fund on improvements to the Labour Force Survey.