On Measuring Bias in Online Information

Bias in online information has recently become a pressing issue, with search engines, social networks and recommendation services being accused of exhibiting some form of bias. In this vision paper, we make the case for a systematic approach towards measuring bias. To this end, we discuss formal measures for quantifying the various types of bias, we outline the system components necessary for realizing them, and we highlight the related research challenges and open problems.Comment: 6 pages, 1 figur

Measuring Prices and Price Competition Online: Amazon and Barnes and Noble

Despite the interest in measuring price sensitivity of online consumers, most academic work on Internet commerce is hindered by a lack of data on quantity. In this paper we use publicly available data on the sales ranks of about 20,000 books to derive quantity proxies at the two leading online booksellers. Matching this information to prices, we can directly estimate the elasticities of demand facing both merchants as well as create a consumer price index for online books. The results show significant price sensitivity at both merchants but demand at Barnes and Noble is much more price-elastic than is demand at Amazon. The data also allow us to estimate the magnitude of retail outlet substitution bias in the CPI due to the rise of Internet sales. The estimates suggest that prices online are much more variable than the CPI, which understates inflation by more than double in one period and gets the sign wrong in another.

Direct comparison of contralateral bias and face/scene selectivity in human occipitotemporal cortex

Human visual cortex is organised broadly according to two major principles: retinotopy (the spatial mapping of the retina in cortex) and category-selectivity (preferential responses to specific categories of stimuli). Historically, these principles were considered anatomically separate, with retinotopy restricted to the occipital cortex and category-selectivity emerging in the lateral-occipital and ventral-temporal cortex. However, recent studies show that category-selective regions exhibit systematic retinotopic biases, for example exhibiting stronger activation for stimuli presented in the contra- compared to the ipsilateral visual field. It is unclear, however, whether responses within category-selective regions are more strongly driven by retinotopic location or by category preference, and if there are systematic differences between category-selective regions in the relative strengths of these preferences. Here, we directly compare contralateral and category preferences by measuring fMRI responses to scene and face stimuli presented in the left or right visual field and computing two bias indices: a contralateral bias (response to the contralateral minus ipsilateral visual field) and a face/scene bias (preferred response to scenes compared to faces, or vice versa). We compare these biases within and between scene- and face-selective regions and across the lateral and ventral surfaces of the visual cortex more broadly. We find an interaction between surface and bias: lateral surface regions show a stronger contralateral than face/scene bias, whilst ventral surface regions show the opposite. These effects are robust across and within subjects, and appear to reflect large-scale, smoothly varying gradients. Together, these findings support distinct functional roles for the lateral and ventral visual cortex in terms of the relative importance of the spatial location of stimuli during visual information processing. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00429-021-02411-8

Direct comparison of contralateral bias and face/scene selectivity in human occipitotemporal cortex

Human visual cortex is organised broadly according to two major principles: retinotopy (the spatial mapping of the retina in cortex) and category-selectivity (preferential responses to specific categories of stimuli). Historically, these principles were considered anatomically separate, with retinotopy restricted to the occipital cortex and category-selectivity emerging in the lateral-occipital and ventral-temporal cortex. However, recent studies show that category-selective regions exhibit systematic retinotopic biases, for example exhibiting stronger activation for stimuli presented in the contra- compared to the ipsilateral visual field. It is unclear, however, whether responses within category-selective regions are more strongly driven by retinotopic location or by category preference, and if there are systematic differences between category-selective regions in the relative strengths of these preferences. Here, we directly compare contralateral and category preferences by measuring fMRI responses to scene and face stimuli presented in the left or right visual field and computing two bias indices: a contralateral bias (response to the contralateral minus ipsilateral visual field) and a face/scene bias (preferred response to scenes compared to faces, or vice versa). We compare these biases within and between scene- and face-selective regions and across the lateral and ventral surfaces of the visual cortex more broadly. We find an interaction between surface and bias: lateral surface regions show a stronger contralateral than face/scene bias, whilst ventral surface regions show the opposite. These effects are robust across and within subjects, and appear to reflect large-scale, smoothly varying gradients. Together, these findings support distinct functional roles for the lateral and ventral visual cortex in terms of the relative importance of the spatial location of stimuli during visual information processing. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00429-021-02411-8

Two dimensional rate gyro bias estimation for precise pitch and roll attitude determination utilizing a dual arc accelerometer array

In this thesis, a previously developed, novel one-dimensional attitude estimation device is expanded through the development and implementation of an innovative method for estimation of two-dimensional attitude making use of a unique low-cost, dual arc accelerometer array measuring longitudinal and transverse rotational rates in real-time. The device and method proposed is an expansion of a previously developed method for one-dimensional attitude determination and rate gyro bias estimation utilizing a one-dimensional accelerometer array. This new revolutionary device utilizes a dual arc accelerometer array and an algorithm for accurate and reliable two-dimensional attitude determination and rate gyro bias estimation in real-time. The method determines the local gravitational field vector from which attitude information can be resolved. Upon determining the location of the local gravitational field vector relative to two consecutive accelerometer sensors, the orientation of the device may then be estimated and the attitude determined. However, this measurement is discrete in nature; therefore, integrated rate gyro measurements are used to determine attitude information resulting in a continuous signal. However, attitude estimates and measurements produced by instantaneous rate sensors and gyroscope integration tend to drift over time due to drift and bias inherent to the rate gyro sensor. The integration of the acquired instantaneous rate signals amplify measurement errors leading to an undependable and imprecise estimate of the vehicles true attitude and orientation. A method for compensation of these errors is proposed in this work resulting in a highly accurate and continuous attitude estimate. For this thesis, simulations of the proposed method and device will be conducted with the inclusion of characteristic, real-world sensor noise and bias estimates produced from corrupted and biased sensors to analyze and assess the feasibility and validity of the proposed method and system configuration for two-dimensional attitude determination. The end goal of this work is to produce a precise and reliable longitudinal and transverse attitude estimation array capable of measuring rate senor and gyro bias online so as to produce highly accurate and reliable pitch and roll angle tracking in real-time while under subjection to simulated flight conditions and scenarios. While this thesis is an expansion of a previously developed device and method, it is a departure from past works in that a new, two-dimensional accelerometer array arc is utilized and additional rotational dimensions are being included in the simulated analysis

Quantifying Biases in Online Information Exposure

Our consumption of online information is mediated by filtering, ranking, and recommendation algorithms that introduce unintentional biases as they attempt to deliver relevant and engaging content. It has been suggested that our reliance on online technologies such as search engines and social media may limit exposure to diverse points of view and make us vulnerable to manipulation by disinformation. In this paper, we mine a massive dataset of Web traffic to quantify two kinds of bias: (i) homogeneity bias, which is the tendency to consume content from a narrow set of information sources, and (ii) popularity bias, which is the selective exposure to content from top sites. Our analysis reveals different bias levels across several widely used Web platforms. Search exposes users to a diverse set of sources, while social media traffic tends to exhibit high popularity and homogeneity bias. When we focus our analysis on traffic to news sites, we find higher levels of popularity bias, with smaller differences across applications. Overall, our results quantify the extent to which our choices of online systems confine us inside "social bubbles."Comment: 25 pages, 10 figures, to appear in the Journal of the Association for Information Science and Technology (JASIST

Patients’ online descriptions of their experiences as a measure of healthcare quality

Introduction Patients are describing their healthcare experiences online using rating websites. There has been substantial professional opposition to this, but the government in England has promoted the idea as a mechanism to improve healthcare quality. Little is known about the content and effect of healthcare rating and review sites. This thesis aims to look at comments left online and assess whether they might be a useful measure of healthcare quality. Method I used a variety of different approaches to examine patients’ comments and ratings about care online. I performed an examination of the comments left on the NHS Choices website, and analysed whether there was a relationship between the comments and traditional patient surveys or other measures of clinical quality. I used discrete choice experiments to look at the value patients place on online care reviews when making decisions about which hospital to go to. I used natural language processing techniques to explore the comments left in free text reviews. I analysed the tweets sent to NHS hospitals in England over a year to see if they contained useful information for understanding care quality. Results The analysis of ratings on NHS Choices demonstrates that reviews left online are largely positive. There are associations between online ratings and both traditional survey methods of patient experience and outcome measures. There is evidence of a selection bias in those who both read and contribute ratings online – with younger age groups and those with higher educational attainment more likely to use them. Discrete choice experiments suggest that people will use online ratings in their decisions about where to seek care, and the effect is similar to that of a recommendation by friends and family. I found that sentiment analysis techniques can be used classify free text comments left online into meaningful information that relates to data in the national patient surveys. However, the analysis of comments on Twitter found that only 11% of tweets were related to care quality. Conclusions Patients rating their care online may have a useful role as a measure of care quality. It has some drawbacks, not least the non-random group of people who leave their comments. However, it provides information that is complementary to current approaches to measuring quality and patient experiences, may be used by patients in their decision-making, and provides timely information for quality improvement. I hypothesise that it is possible to measure a ‘cloud of patient experience’ from all of the sources where patients describe their care online, including social media, and use this to make inferences about care quality. I find this idea has potential, but there are many technical and practical limitations that need to be overcome before it is useful.Open Acces