Quality in Measurement: Beyond the deployment barrier

Network measurement stands at an intersection in the development of the science. We explore possible futures for the area and propose some guidelines for the development of stronger measurement techniques. The paper concludes with a discussion of the work of the NLANR and WAND network measurement groups including the NLANR Network Analysis Infrastructure, AMP, PMA, analysis of Voice over IP traffic and separation of HTTP delays into queuing delay, network latency and server delay

Did inflation really soar after the euro cash changeover? Indirect evidence from ATM withdrawals

The introduction of the euro notes and coins in the first two months of 2002 was followed by a lively debate on the alleged inflationary effects of the new currency. In Italy, as in the rest of the euro area, survey-based measures signaled a much sharper rise in inflation than measured by the official price indices, whose quality was called into question. In this paper we gather indirect evidence on the behavior of prices from the analysis of cash withdrawals from ATM and their determinants. Since these data do not rely on official inflation statistics, they provide an independent check for the latter. We present a model in which the relationship between aggregate ATM withdrawals and aggregate expenditure is not homogenous of degree one in the price level, a prediction which is strongly supported by the data. This feature allows us to test the hypothesis that, after the introduction of the euro notes and coins, consumer prices underwent an increase not recorded by official inflation statistics. We do not find evidence in support of this hypothesis.banknotes, currency, euro, inflation.

Compatibility and Pricing with Indirect Network Effects: Evidence from ATMs

Incompatibility in markets with indirect network effects can affect prices if consumers value "mix and match" combinations of complementary network components. In this paper, we examine the effects of incompatibility using data from a classic market with indirect network effects: Automated Teller Machines (ATMs). Our sample covers a period during which higher ATM fees increased incompatibility between ATM cards (which are bundled with deposit accounts) and other banks' ATM machines. A series of hedonic regressions suggests that incompatibility strengthens the relationship between deposit account pricing and own ATMs, and weakens the relationship between deposit account pricing and competitors' ATMs. The effects of incompatibility are stronger in areas with high population density, suggesting that high travel costs increase both the strength of network effects and the importance of incompatibility in ATM markets.

A methodical approach to performance measurement experiments : measure and measurement specification

This report describes a methodical approach to performance measurement experiments. This approach gives a blueprint for the whole trajectory from the notion of performance measures and how to define them via planning, instrumentation and execution of the experiments to interpretation of the results. The first stage of the approach, Measurement Initialisation, has been worked out completely. It is shown that a well-defined system description allows a procedural approach to defining performance measures and to identifying parameters that might affect it. For the second stage of the approach, Measurement Planning, concepts are defined that enable a clear experiment description or specification. It is highlighted what actually is being measured when executing an experiment. A brief example that illustrates the value of the method and a comparison with an existing method - that of Jain - complete this report

Air Traffic Management Safety Challenges

The primary goal of the Air Traffic Management (ATM) system is to control accident risk. ATM safety has improved over the decades for many reasons, from better equipment to additional safety defences. But ATM safety targets, improving on current performance, are now extremely demanding. Safety analysts and aviation decision-makers have to make safety assessments based on statistically incomplete evidence. If future risks cannot be estimated with precision, then how is safety to be assured with traffic growth and operational/technical changes? What are the design implications for the USA’s ‘Next Generation Air Transportation System’ (NextGen) and Europe’s Single European Sky ATM Research Programme (SESAR)? ATM accident precursors arise from (eg) pilot/controller workload, miscommunication, and lack of upto- date information. Can these accident precursors confidently be ‘designed out’ by (eg) better system knowledge across ATM participants, automatic safety checks, and machine rather than voice communication? Future potentially hazardous situations could be as ‘messy’ in system terms as the Überlingen mid-air collision. Are ATM safety regulation policies fit for purpose: is it more and more difficult to innovate, to introduce new technologies and novel operational concepts? Must regulators be more active, eg more inspections and monitoring of real operational and organisational practices