Consumer Price Index Data Quality: How Accurate is the U.S. CPI?

The Consumer Price Index (CPI) is an estimate of the average change in prices over time paid by urban consumers for a market basket of consumer goods and n the United States. The CPI is used extensively in many different ways, including three major uses: to adjust historical data, to escalate federal payments and tax brackets, and to adjust rents and wages. It directly affects the lives of Americans, so it must be as accurate as possible. But how accurate is it? If, for example, the CPI measures annual inflation as 2.3 percent, how confident can we be in that estimate? This issue of BEYOND THE NUMBERS looks at some different ways the U.S. Bureau of Labor Statistics (BLS) has responded to questions about the accuracy and precision of the CPI. The first section examines the sampling error of the CPI, and the second section discusses possible sources of bias in the index

Halo Mass Function and the Free Streaming Scale

The nature of structure formation around the particle free streaming scale is still far from understood. Many attempts to simulate hot, warm, and cold dark matter cosmologies with a free streaming cutoff have been performed with cosmological particle-based simulations, but they all suffer from spurious structure formation at scales below their respective free streaming scales -- i.e. where the physics of halo formation is most affected by free streaming. We perform a series of high resolution numerical simulations of different WDM models, and develop an approximate method to subtract artificial structures in the measured halo mass function. The corrected measurements are then used to construct and calibrate an extended Press-Schechter (EPS) model with sharp-$k$ window function and adequate mass assignment. The EPS model gives accurate predictions for the low redshift halo mass function of CDM and WDM models, but it significantly under-predicts the halo abundance at high redshifts. By taking into account the ellipticity of the initial patches and connecting the characteristic filter scale to the smallest ellipsoidal axis, we are able to eliminate this inconsistency and obtain an accurate mass function over all redshifts and all dark matter particle masses covered by the simulations. As an additional application we use our model to predict the microhalo abundance of the standard neutralino-CDM scenario and we give the first quantitative prediction of the mass function over the full range of scales of CDM structure formation.Comment: 16 pages, 10 figures, published in MNRA

Discovering the Data-driven City Breakdown and Literacy in the Installation of the Elm Sensor Network

In this article, we examine the role of environmental big data in the installation of an environmental sensor in a UK city. Taking the installation of the Elm sensor as an empirical case study, we understand the installation as incurring an instance of natural breakdown which reveals the contingent work- ings of the device, and places it in the context of the practices of normalisation and stabilisation of the device. We use this to ask questions about the taken for granted smoothing of outputs and the continual elaboration of use and design, alongside the constructive potential for disruptive digital literacies as a site of intervention. By following, empirically, the installation of the technology, we are led to combine, and re-examine, theoretical lines of reasoning about data competences and relationships, and in turn advocate a form of ‘material politics’

Innocence and nostalgia in conversation analysis: the dynamic relations of tape and transcript

Die Konversationsanalyse (KA) meint 'wissenschaftlicher' zu sein als andere Formen der qualitativen Textanalyse. Dieser Anspruch resultiert aus dem Charakter und den 'internen Beziehungen' der methodologischen Verfahren und analytischen Objekte, die in der KA verwendet werden. Dazu gehört vor allem das Vertrauen in Tonbandaufnahmen von 'natürlichen' Interaktionen und in detaillierte Transkripte. In diesem Beitrag werden wir die Beziehungen zwischen diesen beiden Elementen untersuchen - zwischen dem Gesprochenen bzw. Gehörten und dem Geschriebenen bzw. Gelesenen. Insbesondere stellen wir den Anspruch - der regelmäßig in der aktuellen pädagogischen Literatur auftaucht -, dass das Tonband dem Transkript überlegen sei, in Frage. Diese Überlegenheit scheint ontologisch und epistemologisch: das Tonband als erste Aufzeichnung und als 'Daten'; und die Primärrolle des Tonbandes bei der Beilegung von Kontroversen und bei der Einschärfung einer professionellen KA-Kultur. Wir werden unsere Kritik hieran auf den folgenden drei Wegen umreißen: Das Tonband - vom Hören zum Lesen : die Grundrhetorik des Tonbandes; die Bedeutung des 'Wiederhörens' als empfohlene Analysestrategie; die generelle Epistemologie des 'Hörens'; das Transkript - vom Lesen zum Hören (teilweise): das Transkript als ein nicht anerkanntes Analyseobjekt; die rhetorischen Merkmale eines KA-Transkripts; die Unentbehrlichkeit des Transkripts und die übertriebene Vorstellung der Möglichkeit eines technischen Ersatzes; die generelle Epistemologie des 'Lesens'; der gegenseitige durchdachte (elaborative) Charakter von Tonband und Transkript: die dokumentarische Methode der KA; Wiederhören wie Wiederlesen; das Tonband verändert sich auch; das Fehlen eines Grundobjektes für die KA und die Konsequenzen.This paper attempts an analysis of some of the methodological practices of Conversation Analysis (CA); in particular, tape recording and transcription. The paper starts from the observation that, in the CA literature, these practices, and the analytic objects they create (the tape and the transcript), are accorded different treatment: simply put, for CA the tape is a 'realist' object, while the transcript is a 'constructivist' one. The significance of this difference is explored through an analysis of the dynamics of CA practice. We argue that the 'constructivist transcript' is premised on an understanding of CA as predominantly concerned with maximising its 'analytic utility': a concern of one distinct temporal stage of CA work: that of the 'innocent' apprehension of objects in the 'first time through'. The 'realist tape', in contrast, is based on a different aspect of the work of CA: its quest for greater 'evidential utility', achieved by the 'nostalgic' revisiting of previously produced objects for purposes of checking them against each other; work done in the 'next time through'. We further argue that both the ontology and the epistemology of CA's objects are changed in any next time encounter. We conclude with a cautionary speculation on the currently-projected, transcript-free, digital future of CA

Observing and quoting newsgroup messages: method and phenomenon in the hermeneutic spiral

Observing and quoting newsgroup messages: method and phenomenon in the hermeneutic spira

Fluctuating Pressure Analysis of a 2-D SSME Nozzle Air Flow Test

To better understand the Space Shuttle Main Engine (SSME) startup/shutdown tansients, an airflow test of a two dimensional nozzle was conducted at Marshall Space Flight Center's trisonic wind tunnel. Photographic and other instrumentation show during an SSME start large nozzle shell distortions occur as the Mach disk is passing through the nozzle. During earlier develop of the SSME, this startup transient resulted in low cycle fatigue failure of one of the LH2 feedlines. The two dimensional SSME nozzle test was designed to measure the static and fluctuating pressure environment and color Schlieren video during the startup and shutdown phases of the run profile

Hints against the cold and collisionless nature of dark matter from the galaxy velocity function

The observed number of dwarf galaxies as a function of rotation velocity is significantly smaller than predicted by the standard model of cosmology. This discrepancy cannot be simply solved by assuming strong baryonic feedback processes, since they would violate the observed relation between maximum circular velocity ($v_{\rm max}$) and baryon mass of galaxies. A speculative but tantalising possibility is that the mismatch between observation and theory points towards the existence of non-cold or non-collisionless dark matter (DM). In this paper, we investigate the effects of warm, mixed (i.e warm plus cold), and self-interacting DM scenarios on the abundance of dwarf galaxies and the relation between observed HI line-width and maximum circular velocity. Both effects have the potential to alleviate the apparent mismatch between the observed and theoretical abundance of galaxies as a function of $v_{\rm max}$. For the case of warm and mixed DM, we show that the discrepancy disappears, even for luke-warm models that evade stringent bounds from the Lyman-$\alpha$ forest. Self-interacting DM scenarios can also provide a solution as long as they lead to extended ($\gtrsim 1.5$ kpc) dark matter cores in the density profiles of dwarf galaxies. Only models with velocity-dependent cross sections can yield such cores without violating other observational constraints at larger scales.Comment: Matches published versio

An Assessment of Ares I-X Aeroacoustic Measurements with Comparisons to Pre-Flight Wind Tunnel Test Results

During the recent successful launch of the Ares I-X Flight Test Vehicle, aeroacoustic data was gathered at fifty-seven locations along the vehicle as part of the Developmental Flight Instrumentation. Several of the Ares I-X aeroacoustic measurements were placed to duplicate measurement locations prescribed in pre-flight, sub-scale wind tunnel tests. For these duplicated measurement locations, comparisons have been made between aeroacoustic data gathered during the ascent phase of the Ares I-X flight test and wind tunnel test data. These comparisons have been made at closely matching flight conditions (Mach number and vehicle attitude) in order to preserve a one-to-one relationship between the flight and wind tunnel data. These comparisons and the current wind tunnel to flight scaling methodology are presented and discussed. The implications of using wind tunnel test data scaled under the current methodology to predict conceptual launch vehicle aeroacoustic environments are also discussed