Comparisons of echo-integration performance from two multiplexed echosounders

A time-series of acoustically derived aquatic biomass estimates relies on the acoustic equipment maintaining the same performance throughout the time-series. This is normally achieved through a regular calibration process. When the acoustic equipment changes it is necessary to verify that the new equipment produces a similar result to the old equipment, otherwise an unknown bias can be introduced into the time-series. The commonly used Simrad EK60 echosounder has been superseded by the Simrad EK80 echosounder and the performance of these two scientific echosounder systems was compared using interleaved pinging through the same transducer. This was repeated for multiple transducer frequencies (18, 38, 70, 120, and 200 kHz) and from two vessels (Norway’s G.O. Sars in the North Sea and The Netherlands’ Tridens in the Northeast Atlantic Ocean). The broadband facility of the EK80 was not used. Regressions of the grid-integrated backscatter from the two systems were highly linear. The difference in area backscattering coefficients in typical survey conditions was less than 0.6 dB (12%) at the main survey frequency of 38 kHz. In most conventional fish acoustic surveys, the observed differences are less than other sources of survey bias and uncertainty.

Using data from a behavioural survey of men who have sex with men (MSM) to estimate the number likely to present for HIV pre-exposure prophylaxis (PrEP) in Ireland, 2017

In Ireland, men who have sex with men (MSM) have increased HIV risk. Pre-exposure prophylaxis (PrEP), combined with safe sex practices, can reduce HIV acquisition. We estimated MSM numbers likely to present for PrEP by applying French PrEP criteria to Irish MSM behavioural survey data. We adjusted for survey bias, calculated proportions accessing testing services and those likely to take PrEP. We estimated 1–3% of MSM in Ireland were likely to present for PrEP.

Perceptions of Corruption: An Empirical Study Controlling for Survey Bias

Survey data on corruption are widely used to construct corruption indices, but are hardly questioned. How do individual experiences shape perceptions of corruption? Do more work-engaged respondents perceive corruption as a bigger obstacle to business operations than others? What role does answer bias play in corruption surveys? This article brings together several strands of literature to discuss these questions, and tests them empirically with survey data from Bangladesh and Sri Lanka. We find that individuals who are more work engaged report corruption as a bigger obstacle. So did respondents who were previously exposed to corruption. We control for possible answer bias by implementing a randomized response technique, and find that corruption tends to be under-reported. The effects of work engagement and prior exposure to corruption are more pronounced when the bias indicator is considered, and again become stronger once we control for answer bias affecting past experiences with corruption. JEL: C83, D03, D73, O12

Measuring Group Consciousness

Although group consciousness is an important concept in explaining political behavior, both theoretical guidance on how to measure group consciousness and empirical consensus regarding its operationalization are lacking. This has the potential to lead to both diverging results and inaccurate empirical conclusions, which greatly limits the ability to understand the role that group consciousness plays in politics. Using data from Pew’s 2013 “Survey of LGBT Americans,” this analysis provides a foundation for measuring group consciousness using item response theory (IRT). Through an examination of dimensionality, monotonicity, model fit, and differential item functioning, the results demonstrate that many assumptions about measuring group consciousness have been incorrect. Further, the findings suggest that previous conclusions about subgroup differences may be the result of survey bias, rather than actual between-group differences. Moving forward, scholars of political behavior should use IRT to measure latent constructs.