Proxy (statistics)

About: Proxy (statistics) is a research topic. Over the lifetime, 5257 publications have been published within this topic receiving 94504 citations. The topic is also known as: proxy variable & proxy measurement.

On the energy efficiency of proxy-based traffic shaping for mobile audio streaming

Abstract: We study how much energy can be saved by reshaping audio streaming traffic before receiving at the mobile devices. The rationale is the following: Mobile network interfaces (WLAN and 3G) are in active mode when they transmit or receive data, otherwise they are in idle/sleep mode. To save energy, minimum possible time should be spent in active mode and maximum in idle/sleep mode. It is well known that by reshaping the usually constant bit rate multimedia traffic into bursts, it is possible to spend more time in idle/sleep mode leading to impressive energy savings. We propose a proxy-based solution that shapes an audio stream into bursts before relaying the traffic to the mobile device. The novelty of our work is an evaluation of the energy savings using such a proxy with different configurations for both WLAN access with standard 802.11 Power Saving Mode and 3G access. We conclude that for WLAN access, proxy causes power savings of 30%-65% depending on the audio stream rate, location of the proxy and amount of cross traffic. In the case of 3G, the effectiveness of our proxy seems to vary depending on the phone model and operator. In some cases, the energy savings are encouraging, while in other cases the proxy turns out to be ineffective due to abnormal delay variation and TCP flow control behavior.

On measuring comparative advantage: Further comments

Abstract: Forstner and Murray's (BFM) recent remarks suggest confusion on their part about (i) the motivation for constructing an index of comparative advantage and (ii) the relation between the NCA concept and the definition of comparative advantage upon which my indices are based. As is often the case, much of the confusion can be traced to semantics. Nonetheless, this confusion leads BFM to erroneously question whether the NCA concept is useful for inferring comparative advantages and also to conduct an improper analysis of the bias in a "production intensity" index. The following remarks are intended to point out and resolve these areas of confusion. I believe that most of the recent debate over the NCA concept can be traced to differences in the interpretation of the word "index". Anyone wishing to conduct an empirical study of comparative advantage immediately confronts two questions: How is comparative advantage to be defined and what variable is to be chosen to represent it. Assuming that the answer to these questions leads to the use of trade data, one quickly discovers that a direct comparison of trade volumes is likely to be misleading since both countries and goods differ in their importance in world markets. This leads one to choose a variable that can be used to scale the variable representing comparative advantage. The number that results when the variable chosen to represent comparative advantage is divided by the "scale variable" is what I have called an "index of comparative advantage". In contrast, I think BFM take the word "index" to be synonymous with the word "proxy" and therefore interpret the phrase "index of comparative advantage" to mean the variable representing comparative advantage. The central issue addressed in Bowen [1983; 1985] was the choice of a theoretically consistent scale variable and not the choice of a variable to represent comparative advantage. In particular, both the "net trade" and "production" indices were derived in a model of net trade and thus net trade was necessarily the variable chosen to represent comparative advantage. Within that model, the scale variable Sik = Yi(Qwk/YJ was derived under the assumption of identical and homothetic preference (IHP). Seeking an interpretation of this variable that was consistent with the interpretation given to previous scale variables, the NCA concept was invoked to demonstrate that Sik could be interpreted as the production that would exist in a

Do attitudes expressed in surveys predict ethnic discrimination

Abstract: Survey data on people’s reported attitudes towards ethnic minorities are sometimes used as a proxy for ethnic discrimination. However, there is weak empirical evidence of a link between reported at ...

Socioeconomic strata as proxy variable for household income in transportation research. Evaluation for Bogotá, Medellín, Cali and Barranquilla

Abstract: In Colombia, a socioeconomic stratification (SES) system of households based on the physical characteristics of the dwelling and its surroundings is implemented in order to set subsidies to public services. Many studies use this classification as a proxy variable for the household income, mainly because of the ease to retrieve data. This investigation proposes an evaluation of the SES as an explanatory variable for the household income. Ordered logit regressions were estimated for the cities of Bogota, Medellin, Cali and Barranquilla, where the dependent variable corresponds to the SES. Even though there is a positive correlation between SES and household income, the relation depends on certain characteristics of the household as it size, vehicle availability and percentage of workers and students. The results were validated by comparing trip generation models. By including the significant attributes from the ordinal regressions, trip generation models with income and SES had similar fit, which suggests that using the SES as a proxy variable for the income, might be appropriate as long as their correspondence is checked according to household characteristics.