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The Fibonacci topological order is the prime candidate for the realization of universal topological quantum computation. We devise minimal quantum circuits to demonstrate the non-Abelian nature of the doubled Fibonacci topological order, as realized in the Levin-Wen string net model. Our circuits effectively initialize the ground state, create excitations, twist and braid them, all in the smallest lattices possible. We further design methods to determine the fusion amplitudes and braiding phases of multiple excitations by carrying out a single qubit measurement. We show that the fusion channels of the doubled Fibonacci model can be detected using only three qubits, twisting phases can be measured using five, and braiding can be demonstrated using nine qubits. These designs provide the simplest possible settings for demonstrating the properties of Fibonacci anyons and can be used as realistic blueprints for implementation on many modern quantum architectures., Comment: 20 pages, 15 figures

The proliferation of low-cost sensors in smartphones has facilitated numerous applications; however, large-scale deployments often encounter performance issues. Sensing heterogeneity, which refers to varying data quality due to factors such as device differences and user behaviors, presents a significant challenge. In this research, we perform an extensive analysis of 3-axis accelerometer data from the MyShake system, a global seismic network utilizing smartphones. We systematically evaluate the quality of approximately 22 million 3-axis acceleration waveforms from over 81 thousand smartphone devices worldwide, using metrics that represent sampling rate and noise level. We explore a broad range of factors influencing accelerometer data quality, including smartphone and accelerometer manufacturers, phone specifications (release year, RAM, battery), geolocation, and time. Our findings indicate that multiple factors affect data quality, with accelerometer model and smartphone specifications being the most critical. Additionally, we examine the influence of data quality on earthquake parameter estimation and show that removing low-quality accelerometer data enhances the accuracy of earthquake magnitude estimation., Comment: This paper has been submitted before but got rejected, since we don't have time to revise it, we just post it as a pre-print

This paper presents a novel approach to extract scientifically valuable information about Earth's physical phenomena from unconventional sources, such as multi-modal social media posts. Employing a state-of-the-art large language model (LLM), Gemini 1.5 Pro (Reid et al. 2024), we estimate earthquake ground shaking intensity from these unstructured posts. The model's output, in the form of Modified Mercalli Intensity (MMI) values, aligns well with independent observational data. Furthermore, our results suggest that LLMs, trained on vast internet data, may have developed a unique understanding of physical phenomena. Specifically, Google's Gemini models demonstrate a simplified understanding of the general relationship between earthquake magnitude, distance, and MMI intensity, accurately describing observational data even though it's not identical to established models. These findings raise intriguing questions about the extent to which Gemini's training has led to a broader understanding of the physical world and its phenomena. The ability of Generative AI models like Gemini to generate results consistent with established scientific knowledge highlights their potential to augment our understanding of complex physical phenomena like earthquakes. The flexible and effective approach proposed in this study holds immense potential for enriching our understanding of the impact of physical phenomena and improving resilience during natural disasters. This research is a significant step toward harnessing the power of social media and AI for natural disaster mitigation, opening new avenues for understanding the emerging capabilities of Generative AI and LLMs for scientific applications.

Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the 1D Heisenberg model were conjectured to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we study the probability distribution, $P(\mathcal{M})$, of the magnetization transferred across the chain's center. The first two moments of $P(\mathcal{M})$ show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments rule out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide key insights into universal behavior in quantum systems.

Indistinguishability of particles is a fundamental principle of quantum mechanics. For all elementary and quasiparticles observed to date - including fermions, bosons, and Abelian anyons - this principle guarantees that the braiding of identical particles leaves the system unchanged. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well developed mathematical description of non-Abelian anyons and numerous theoretical proposals, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. While efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasi-particles, superconducting quantum processors allow for directly manipulating the many-body wavefunction via unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons, we implement a generalized stabilizer code and unitary protocol to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of employing the anyons for quantum computation and utilize braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and - through the future inclusion of error correction to achieve topological protection - could open a path toward fault-tolerant quantum computing.

Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low in order for logical performance to improve with increasing code size. Here, we report the measurement of logical qubit performance scaling across multiple code sizes, and demonstrate that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number. We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle ($2.914\%\pm 0.016\%$ compared to $3.028\%\pm 0.023\%$). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a $1.7\times10^{-6}$ logical error per round floor set by a single high-energy event ($1.6\times10^{-7}$ when excluding this event). We are able to accurately model our experiment, and from this model we can extract error budgets that highlight the biggest challenges for future systems. These results mark the first experimental demonstration where quantum error correction begins to improve performance with increasing qubit number, illuminating the path to reaching the logical error rates required for computation., Comment: Main text: 6 pages, 4 figures. v2: Update author list, references, Fig. S12, Table IV

We present a general method to analyze the topological nature of the domain boundary connectivity that appeared in relaxed moir\'e superlattice patterns at the interface of 2-dimensional (2D) van der Waals (vdW) materials. At large enough moir\'e lengths, all moir\'e systems relax into commensurated 2D domains separated by networks of dislocation lines. The nodes of the 2D dislocation line network can be considered as vortex-like topological defects. We find that a simple analogy to common topological systems with an $S^1$ order parameter, such as a superconductor or planar ferromagnet, cannot correctly capture the topological nature of these defects. For example, in twisted bilayer graphene, the order parameter space for the relaxed moir\'e system is homotopy equivalent to a punctured torus. Here, the nodes of the 2D dislocation network can be characterized as elements of the fundamental group of the punctured torus, the free group on two generators, endowing these network nodes with non-Abelian properties. Extending this analysis to consider moir\'e patterns generated from any relative strain, we find that antivortices occur in the presence of anisotropic heterostrain, such as shear or anisotropic expansion, while arrays of vortices appear under twist or isotropic expansion between vdW materials. Experimentally, utilizing the dark field imaging capability of transmission electron microscopy (TEM), we demonstrate the existence of vortex and antivortex pair formation in a moir\'e system, caused by competition between different types of heterostrains in the vdW interfaces. We also present a methodology for mapping the underlying heterostrain of a moir\'e structure from experimental TEM data, which provides a quantitative relation between the various components of heterostrain and vortex-antivortex density in moir\'e systems., Comment: 15 pages with 11 figures

MyShake is a free citizen science smartphone app that provides a range of features related to earthquakes. Features available globally include rapid post-earthquake notifications, live maps of earthquake damage as reported by MyShake users, safety tips and various educational features. The app also uses the accelerometer to detect earthquake shaking and to record and submit waveforms to a central archive. In addition, MyShake delivers earthquake early warning alerts in California, Oregon and Washington. In this study we compare the felt shaking reports provided by MyShake users in California with the US Geological Survey's "Did You Feel It?" intensity reports. The MyShake app simply asks "What strength of shaking did you feel" and users report on a five-level scale. When the reports are averaged in spatial bins, we find strong correlations with the Modified Mercalli Intensity scale values reported by the USGS based on the much more complex DYFI surveys. The MyShake felt reports can therefore also be used to generate shaking intensity maps.

In this paper, we provide a comprehensive overview of a recent debate over the quantum versus classical solvability of bounded distance decoding (BDD). Specifically, we review the work of Eldar and Hallgren [EH22], [Hal21] demonstrating a quantum algorithm solving $\lambda_1 2^{-\Omega(\sqrt{k \log q})}$-BDD in polynomial time for lattices of periodicity $q$, finite group rank $k$, and shortest lattice vector length $\lambda_1$. Subsequently, we prove the results of [DvW21a], [DvW21b] with far greater detail and elaboration than in the original work. Namely, we show that there exists a deterministic, classical algorithm achieving the same result.

We demonstrate a microfabricated optomechanical accelerometer that is capable of percent-level accuracy without external calibration. To achieve this capability, we use a mechanical model of the device behavior that can be characterized by the thermal noise response along with an optical frequency comb readout method that enables high sensitivity, high bandwidth, high dynamic range, and SI-traceable displacement measurements. The resulting intrinsic accuracy was evaluated over a wide frequency range by comparing to a primary vibration calibration system and local gravity. The average agreement was found to be 2.1 % for the calibration system between 0.1 kHz and 15 kHz and better than 0.2 % for the static acceleration. This capability has the potential to replace costly external calibrations and improve the accuracy of inertial guidance systems and remotely deployed accelerometers. Due to the fundamental nature of the intrinsic accuracy approach, it could be extended to other optomechanical transducers, including force and pressure sensors., Comment: 13 pages, 7 figures

After significant earthquakes, we can see images posted on social media platforms by individuals and media agencies owing to the mass usage of smartphones these days. These images can be utilized to provide information about the shaking damage in the earthquake region both to the public and research community, and potentially to guide rescue work. This paper presents an automated way to extract the damaged building images after earthquakes from social media platforms such as Twitter and thus identify the particular user posts containing such images. Using transfer learning and ~6500 manually labelled images, we trained a deep learning model to recognize images with damaged buildings in the scene. The trained model achieved good performance when tested on newly acquired images of earthquakes at different locations and ran in near real-time on Twitter feed after the 2020 M7.0 earthquake in Turkey. Furthermore, to better understand how the model makes decisions, we also implemented the Grad-CAM method to visualize the important locations on the images that facilitate the decision.

A set partition $\sigma$ of $[n]=\{1,\cdots ,n\}$ contains another set partition $\omega$ if a standardized restriction of $\sigma$ to a subset $S\subseteq[n]$ is equivalent to $\omega$. Otherwise, $\sigma$ avoids $\omega$. Sagan and Goyt have determined the cardinality of the avoidance classes for all sets of patterns on partitions of $[3]$. Additionally, there is a bijection between the set partitions and restricted growth functions (RGFs). Wachs and White defined four fundamental statistics on those RGFs. Sagan, Dahlberg, Dorward, Gerhard, Grubb, Purcell, and Reppuhn consider the distributions of these statistics over various avoidance classes and they obtained four variate analogues of the previously cited cardinality results. They did the first thorough study of these distributions. The analogues of their many results follows for set partitions with exactly $k$ blocks for a specified positive integer $k$. These analogues are discussed in this work., Comment: Original Research

The MyShake project aims to build a global smartphone seismic network to facilitate large-scale earthquake early warning and other applications by leveraging the power of crowdsourcing. The MyShake mobile application first detects earthquake shaking on a single phone. The earthquake is then confirmed on the MyShake servers using a "network detection" algorithm that is activated by multiple single-phone detections. In part two of this two paper series, we report the first order performance of MyShake's Earthquake Early Warning (EEW) capability in various selected locations around the world. Due to the present sparseness of the MyShake network in most parts of the world, we use our simulation platform to understand and evaluate the system's performance in various tectonic settings. We assume that 0.1% of the population has the MyShake mobile application installed on their smartphone, and use historical earthquakes from the last 20 years to simulate triggering scenarios with different network configurations in various regions. Then, we run the detection algorithm with these simulated triggers to understand the performance of the system. The system performs best in regions featuring high population densities and onshore, upper crustal earthquakes M<7.0. In these cases, alerts can be generated ~4-6 sec after the origin time, magnitude errors are within ~0.5 magnitude units, and epicenters are typically within 10 km of true locations. When the events are offshore or in sparsely populated regions, the alerts are slower and the uncertainties in magnitude and location increase. Furthermore, even with 0.01% of the population as the MyShake users, in regions of high population density, the system still performs well for earthquakes larger than M5.5. For details of the simulation platform and the network detection algorithm, please see part one of this two paper series., Comment: 13 figures, submitted to Seismological Research Letters

The MyShake project aims to build a global smartphone seismic network to facilitate large-scale earthquake early warning and other applications by leveraging the power of crowdsourcing. The MyShake mobile application first detects earthquake shaking on a single phone. The earthquake is then confirmed on the MyShake servers using a "network detection" algorithm that is activated by multiple single-phone detections. In this part one of the two paper series, we present a network detection algorithm and a simulation platform to test earthquake scenarios at various locations around the world. The proposed network detection algorithm is built on the DBSCAN classic spatial clustering algorithm, with modifications to take temporal characteristics into account and the association of new triggers. We test our network detection algorithm using real data recorded by MyShake users during the M4.4 January 4th, 2018, Berkeley and the M5.2 June 10th, 2016, Borrego Springs earthquakes to demonstrate the system's utility. In order to test the entire detection procedure and to understand the first order performance of MyShake in various locations around the world representing different population and tectonic characteristics, we then present a software platform which can simulate earthquake triggers in hypothetical MyShake networks. Part two of this paper series explores our MyShake early warning simulation performance in selected regions around the world., Comment: 7 figures, Submitted to Seismological Research Letters

MyShake harnesses private/personal smartphones to build a global seismic network. It uses the accelerometers embedded in all smartphones to record ground motions induced by earthquakes, returning recorded waveforms to a central repository for analysis and research. A demonstration of the power of citizen science, MyShake expanded to 6 continents within days of being launched, and has recorded 757 earthquakes in the first 2 years of operation. The data recorded by MyShake phones has the potential to be used in scientific applications, thereby complementing current seismic networks. In this paper: (1) we report the capabilities of smartphone sensors to detect earthquakes by analyzing the earthquake waveforms collected by MyShake. (2) We determine the maximum epicentral distance at which MyShake phones can detect earthquakes as a function of magnitude. (3) We then determine the capabilities of the MyShake network to estimate the location, origin time, depth and magnitude of earthquakes. In the case of earthquakes for which MyShake has provided 4 or more phases (21 events), either P- or S-wave signals, and has an azimuthal gap less than 180 degrees, the median location, origin time and depth errors are 2.7 km, 0.2 s, and 0.1 km respectively relative to USGS global catalog locations. Magnitudes are also estimated and have a mean error of 0.0 and standard deviation 0.2. These preliminary results suggest that MyShake could provide basic earthquake catalog information in regions that currently have no traditional networks. With an expanding MyShake network, we expect the event detection capabilities to improve and provide useful data on seismicity and hazards., Comment: Submitted to Seismological Research Letters, 10 figures, 3 tables

Earthquake Early Warning (EEW) systems can effectively reduce fatalities, injuries, and damages caused by earthquakes. Current EEW systems are mostly based on traditional seismic and geodetic networks, and exist only in a few countries due to the high cost of installing and maintaining such systems. The MyShake system takes a different approach and turns people's smartphones into portable seismic sensors to detect earthquake-like motions. However, to issue EEW messages with high accuracy and low latency in the real world, we need to address a number of challenges related to mobile computing. In this paper, we first summarize our experience building and deploying the MyShake system, then focus on two key challenges for smartphone-based EEW (sensing heterogeneity and user/system dynamics) and some preliminary exploration. We also discuss other challenges and new research directions associated with smartphone-based seismic network., Comment: 6 pages, conference paper, already accepted at hotmobile 2019

We present total and specular reflectance measurements of various materials that are commonly (and uncommonly) used to provide baffling and/or to minimize the effect of stray light in optical systems. More specifically, we investigate the advantage of using certain black surfaces and their role in suppressing stray light on detectors in optical systems. We measure the total reflectance of the samples over a broad wavelength range (250 < lambda < 2500 nm) that is of interest to astronomical instruments in the ultraviolet, visible, and near-infrared regimes. Additionally, we use a helium-neon laser to measure the specular reflectance of the samples at various angles. Finally, we compare these two measurements and derive the specular fraction for each sample.

DECal is a new calibration system for the CTIO 4 m Blanco telescope. It is currently being installed as part of the Dark Energy Survey and will provide both broadband flat fields and narrowband (about 1 nm bandwidth) spectrophotometric calibration for the new Dark Energy Camera (DECam). Both of these systems share a new Lambertian flat field screen. The broadband flat field system uses LEDs to illuminate each photometric filter. The spectrophotometric calibration system consists of a monochromator-based tunable light source that is projected onto the flat field screen using a custom line-to-spot fiber bundle and an engineered diffuser. Several calibrated photodiodes positioned along the beam monitor the telescope throughput as a function of wavelength. This system will measure the wavelength-dependent instrumental response function of the total telescope+instrument system in the range 300 < lambda < 1100nm. The spectrophotometric calibration will be performed regularly (roughly once per month) to determine the spectral response of the DECam system and to monitor changes in instrumental throughput during the five year Dark Energy Survey project., Comment: 10 pages, 5 figures. To appear in conference proceedings: "Calibration and Standardization of Large Surveys and Missions in Astronomy and Astrophysics" (Fermilab, April 16-19, 2012)

Using the Faint Object Spectrograph (FOS) aboard the Hubble Space Telescope, we have obtained the first time-resolved spectra of the King et al. ultraviolet-bright counterpart to the 11-minute binary X-ray source in the core of the globular cluster NGC 6624. This object cannot be readily observed in the visible, even from HST, due to a much brighter star superposed <0.1'' distant. Our FOS data show a highly statistically significant UV flux modulation with a period of 11.46+-0.04 min, very similar to the 685 sec period of the known X-ray modulation, definitively confirming the association between the King et al. UV counterpart and the intense X-ray source. The UV amplitude is very large compared with the observed X-ray oscillations: X-ray variations are generally reported as 2-3% peak-to-peak, whereas our data show an amplitude of about 16% in the 126-251 nm range. A model for the system by Arons & King predicts periodic UV fluctuations in this shortest-known period binary system, due to the cyclically changing aspect of the X-ray heated face of the secondary star (perhaps a very low mass helium degenerate). However, prior to our observations, this predicted modulation has not been detected. Employing the Arons & King formalism, which invokes a number of different physical assumptions, we infer a system orbital inclination 35deg

This paper investigates the media attitudes and behaviors of black adults toward four types of print media: majority, black entertainment, black establishment, and black nonestablishment. The relationships of demographic and socioeconomic characteristics, subjective orientations, and media attitudes and behaviors are empirically examined. Consistent with past research, but with more precise measurement and within a multivariate specification, it was found that those of a higher socioeconomic status tended to read more magazines and print media in general, save black entertainment magazines. Overall, the relationships between all of the media variables pointed to the utility of making certain distinctions within the black press, and to the adequacy of simultaneously incorporating subjective orientations and demographic and socioeconomic characteristics as predictor variables. (Author/AM)

This study explores differences among black adults in their attitudes and behavior towards television and the social processes which determine these differences. A recursive structural equation model was employed to interpret patterns of direct and indirect effects among a set of variables representing demographic and socioeconomic characteristics, general and race-related attitudes, television exposure, preference, and evaluation. Results indicate that variation in attitudes and behaviors toward television (especially those related to perceived bias and perceived bad points of black-oriented situation comedies) is systematically related to differences among black adults in their exposure to the medium, subjective orientations, and demographic and socioeconomic characteristics. One of the most powerful predictors in the model was education. A relationship was detected between education and every television attitude and behavior, save choice of black-oriented shows as favorite. The effects of education on viewing selectively, public affairs viewing, perception of bias in television, and evaluation of one kind of black-oriented programming suggest that differences among blacks in the intellectual climate surrounding television attitudes and behavior may contribute substantially to differences among blacks in attitudes and behaviors. (Author/AM)

Data from personal interviews with 268 black adults living in predominantly black neighborhoods of San Francisco, California, were used to examine the relationships among political participation, media exposure, and various individual characteristics. Results showed that reading general news magazines had the strongest interaction with the three political involvement variables, reaching statistical significance in every equation. Another consistent predictor was the reading of black-oriented news magazines. Viewing black-oriented public affairs television programs was specifically associated with campaign participation. Exposure to general public affairs on television was notable for its consistent lack of association with any of the political participation variables. The only noteworthy predictors of media use were age and education, while news magazine and newspaper use are associated with higher income, but not significantly so. Psychological measures in the study made minimal contributions to the understanding of blacks' political participation. These findings suggest that media exposure, rather than being an independent variable, facilitates the activation of background and psychological variables into political participation. (RL)

A study was conducted to examine the background factors related to two racial attitudes of blacks--black identity and alienation from white society in the United States--and to investigate the relationship between these two conceptually different notions of black racial attitudes. An area probability design was employed and 324 black adults living in the San Francisco, California, area were interviewed. Demographic and socioeconomic factors elicited were (1) age, (2) occupation, (3) income, (4) education, (5) perceived social class, and (6) sex. The subjects each completed a six-item agree-disagree scale measuring alienation from white society and a seven-item agree-disagree scale measuring black identity. The results indicated that younger blacks were more alienated from white society than were older blacks. Moreover, the younger, the more highly educated, and those of perceived lower social class all tended to have higher black identity. Although the correlation between black identity and alienation from white society was high, an analysis of the relationship of the background variables to the two indicated that they were conceptually distinct. (Author/FL)

The techniques for calculating marginal costs in higher education are examined in detail. Marginal costs, as defined in economics, is the change in total cost associated with producing one additional unit of output. In higher education, the most frequently selected unit of output is a full-time-equivalent student or, alternatively, a student credit hour. After reviewing several aspects of the microeconomic theory of costs, detailed analysis is provided of the three basic methods of estimating marginal costs: the regression method, the fixed- and variable-cost method, and the incremental-cost method. For each method, definitions and examples of cost calculations are provided, along with information on data and analytical requirements and strengths/weaknesses. In addition, a literature review is included that indicates the following: the use of statistical costs analysis in which marginal costs are estimated is essentially the same sort of undertaking in higher education as it is in other enterprises, such as business and industry, hospitals, and primary and secondary education; the typical approach to developing specific costs functions has been pragmatic; and basic elements of the microeconomic model are seldom realized in applied work. (SW)

A report based on a conference on the impact of cost information on statewide budgeting and planning is presented. The conference was organized around case-study reports on the use of cost information in higher education budgeting in Florida, Indiana, Washington, and Wisconsin. Rather than publishing convention proceedings, the case studies were further investigated. Interviews were conducted with institutional staff, state postsecondary education agency staff, executive budget staff, and legislative staffs in each state, and available documentation on costing and budgeting was collected. Information gathered from these sources and from conference papers was put together to develop a case study of costing and budgeting in each state, with a particular focus on innovationand the requirements expected to characterize the environment for higher education in the 1980s. This report also contains a chapter by Harold L. Enarson on the uses and abuses of cost information. He cautions against overemphasis of the value of cost information. A second chapter by Frank B. Pesci provides an overview of the issues in statewide planning and appropriations processes and the relationship of cost information to these issues from the perspective of a state senator. The final chapter of the report presents the editors' views on cost-driven formulas and attempts to draw conclusions from the case studies. (SW)

This paper reviews the role of television in the lives of blacks and suggests approaches on how to improve the quality of communication research. Portrayals, exposure patterns, attitudes and motives, and effects of blacks on television are discussed. It is suggested that future research should emphasize interpretive analysis or assessment of the meaning of program content as it relates to black cultural experiences. It is further claimed that: (1) blacks are increasingly presented on television, but the quality of presentations tends to be stereotypical; (2) blacks have different viewing patterns than whites; and (3) those with less education and lower socioeconomic status tend to watch television more and prefer commercial network programs. Attitudinally, blacks appear to have different program preferences and tend to be more positive toward television than whites. Conceptual and methodological shortcomings of past research are identified as: (1) lack of sensitivity to black cultural experiences; (2) too much emphasis on comparative studies; (3) inadequate sample sizes; (4) overemphasis on descriptive investigations as opposed to theoretical or explanatory studies; and (5) the absence of theory. Also presented are outlines for concept and method validation and basic strategies for data collection. (AOS)

A study examined whether mass media exposure is a unidimensional, bidimensional, or multidimensional construct as reflected in commonly used indicators of exposure. Telephone interviews were conducted with 534 households to determine media exposure. A structural equation model was proposed to account for the dimensionality of mass media exposure, the relationship among the identified dimensions, the reliability of the indicators, and the measurement errors involved. Results indicated that the hypothesized multidimensional construct provided the best fit. They also showed that the commonly used indicators of mass media exposure had a statistically significant relationship with their respective constructs, though the indicators exhibited both random and nonrandom measurement error. The results of this study suggest that many of the contradictory results relating mass media exposure to various outcome variables may be due to varying degrees of measurement error, and that more attention should be placed on the assessment of the extant measures of mass media exposure and the development of more adequate ones. A three-page list of references and four tables of data are included. A figure illustrates the multidimensional structure of mass media exposure. (JD)