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Objective: The potential influence (i.e., impact rate) of catch‐and‐release fisheries on wild steelhead Oncorhynchus mykiss is poorly understood and is a function of the abundance of wild fish, how many fish are encountered by anglers (i.e., encounter rate), and the mortality of fish that are caught and released. In Idaho, estimates of wild steelhead encounter rates have been derived using the number of wild and hatchery steelhead passing Lower Granite Dam, the number of hatchery steelhead harvested, and the number of hatchery steelhead caught and released. The method includes assumptions that hatchery and wild steelhead have equal encounter rates and catch‐and‐release mortality is 5% for wild steelhead. Here, we investigated wild and hatchery steelhead encounter rates by anglers, estimated catch‐and‐release mortality, and concatenated both aspects to examine how existing recreational steelhead fisheries influence wild steelhead mortality. Methods: We sampled, tagged, and released 1,251 spawn‐year 2020 (SY2020) and 1,956 spawn‐year 2021 (SY2021) adult steelhead at Lower Granite Dam with T‐bar anchor tags and passive integrated transponder (PIT) tags to estimate steelhead encounter rates and catch‐and‐release mortality. Differences in survival of caught steelhead and those not reported as caught were evaluated using detections at various locations (e.g., PIT arrays, weirs). Result: Estimated encounter rates were 43.7% (95% credible interval; 28.2%, 100.0%) for wild fish and 46.7% (29.6%, 100.0%) for adipose‐clipped fish in SY2020. In SY2021, encounter rates were 47.2% (32.4%, 100.0%) for wild fish and 52.3% (37.1%, 100.0%) for adipose‐clipped fish. Based on detections of caught fish and those not reported as caught, catch‐and‐release mortality of wild steelhead was estimated to be 1.6% (0.0%, 5.2%). Wild steelhead impact rates were 0.7% (0.0%, 2.7%) in SY2020 and 0.7% (0.0%, 2.8%) in SY2021. Conclusion: Estimated rates of impact on wild steelhead were consistent and low across years despite major differences in the structure of the fisheries. Our results suggest assuming that encounter rates are equal between hatchery and wild steelhead, and that steelhead catch‐and‐release mortality is 5%, will likely lead to a conservative estimate of the wild steelhead impact occurring from catch‐and‐release fisheries. Impact statementWith wild steelhead numbers declining in many parts of North America, a dilemma between providing angling opportunity and wild steelhead conservation can develop. We show that encounter rate plays a larger role than mortality regarding catch‐and‐release angling on overall impact rates. Our method provides a direct, reliable estimate of encounter rates across multiple scales. [ABSTRACT FROM AUTHOR]

Objective: Anecdotal evidence suggests that the term "pollster" has, in recent years, become stigmatized in the United States. We explore this and a subsequent question as to whether negative perceptions of pollsters affect people's perceived trustworthiness of survey findings. Methods: Survey experiments were administered to national probability‐based samples after the 2016 and 2020 elections. Results: In each study, pollsters obtained significantly more negative ratings when compared to "survey researchers" and "public opinion researchers," suggesting that the general public views pollsters, who are more likely to be viewed as partisan, as being less honest/ethical. In line with social identity theory, interaction models revealed that those rating pollster critic Donald Trump most favorably had the most negative ratings of pollsters and public opinion researchers, compared to survey researchers. Yet, the vignette experiment showed that negative perceptions of pollsters did not affect the perceived trustworthiness of survey result reports. Conclusions: We conclude that while there appears to be a stigmatization of pollsters, those negative perceptions do not translate into less trust in the findings of public opinion. [ABSTRACT FROM AUTHOR]

One of the distinctions between classical test theory and item response theory is that the former focuses on sum scores and their relationship to true scores, whereas the latter concerns item responses and their relationship to latent scores. Although item response theory is often viewed as the richer of the two theories, sum scores are still often used in practice. The issue addressed here is how to conduct item response modeling when only sum scores are available for some respondents; that is, their item responses are missing, but their sums scores are known. The author reviews the important role of sum scores in item response theory and shows how to estimate item response models using sum scores as data in lieu of item responses. The author also shows how this can be easily implemented in a Bayesian framework using the software package Just Another Gibbs Sampler (JAGS), and provides three examples for illustration.

Food web theory predicts that one of the consequences of oligotrophication is the decline in fisheries following the establishment of nutrient-deficient conditions and low biogenic production. However, emerging evidence suggests that more complex trophic interactions, induced by plankton composition, dietary diversification, temporal and spatial heterogeneity, variations in fish age and size structure can lead to ecosystem responses that deviate from theoretical predictions; especially in the shallow littoral zone. In this study, two end-to-end modelling strategies are used to characterize potential food web structural shifts and overall ecosystem productivity in response to oligotrophication. Our modelling strategy draws upon empirical and theoretical evidence from the Bay of Quinte, a semi-enclosed embayment in northeastern Lake Ontario that has been subjected to phosphorus (P) abatement strategies in the 1970s. We first show that the role of food abundance has been a primary factor shaping fish production, but the fish community gradually responded to the reduced availability of pelagic staples of their diet by displaying greater reliance upon alternative sources, including benthic and other autochthonous (or even allochthonous) food items. Our analysis further suggests that degree of diet overlap between competing trophic guilds can significantly modulate realized biomass levels. The composition of the autotrophic community is another major confounding factor that can induce significant variations from the predicted food web productivity patterns in response to oligotrophication. Overall, our analysis suggests that the proposed reduction of the ambient total phosphorus levels may not necessarily trigger a significant decline in fish biomass in the Bay of Quinte. [ABSTRACT FROM AUTHOR]

Multidimensional item response models are usually implemented to model the relationship between item responses and two or more traits of interest. We show how multidimensional multinomial logit item response models can also be used to account for individual differences in response style. This is done by specifying a factor-analytic model for latent responses at the category level. This permits traits and response style to be separated into separate but possibly correlated factors when properly identified by the factor structure. Special cases of this model can be viewed as generalizations of some unidimensional multinomial logit item response models. In this article, we describe and demonstrate the specification and implementation of these models to account for individual differences in response style that would otherwise compromise the validity of the measurement model. (Contains 5 notes, 2 tables, and 6 figures.)

A multidimensional item response theory model that accounts for response style factors is presented. The model, a multidimensional extension of Bock's nominal response model, is shown to allow for the study and control of response style effects in ordered rating scale data so as to reduce bias in measurement of the intended trait. In the current application, the model is also used to investigate response style as an underlying cause of differential item functioning. The approach is illustrated using the item responses of cigarette smokers to the Wisconsin Inventory of Smoking Dependence Motives, a self-report measure of tobacco dependence. (Contains 3 figures and 5 tables.)

In this paper I present a class of discrete choice models for ordinal response variables based on a generalization of the stereotype model. The stereotype model can be derived and generalized as a random utility model for ordered alternatives. Random utility models can be specified to account for heteroscedastic and correlated utilities. In the case of the generalized stereotype model this includes category-specific random effects due to individual differences in response style. But unlike standard random utility models the generalized stereotype model is better suited for ordinal response variables and can be interpreted as a kind of unidimensional unfolding model. This paper discusses the specification, interpretation, identification, and estimation of generalized stereotype models. Two applications are provided for illustration.

Objective: This study examined the relationships between childhood and family background variables, including sexual and physical abuse, and subsequent alcohol abuse and psychological distress in adult lesbians. Methodology: Structural equation modeling was used to evaluate relationships between childhood sexual and physical abuse and parenting variables and latent measures of lifetime alcohol abuse and psychological distress in a large community-based sample of lesbians. Results: Childhood sexual abuse (CSA) directly predicted lifetime alcohol abuse, and childhood physical abuse (CPA) directly predicted lifetime psychological distress. In addition, CSA indirectly increased the risk of lifetime alcohol abuse through its negative effect on age at first heterosexual intercourse. Childhood physical abuse had only indirect effects on lifetime alcohol abuse through its strong relationship to lifetime psychological distress. Parental drinking problems and parental strictness directly predicted lifetime psychological distress; parental drinking problems indirectly predicted lifetime alcohol abuse through the mediators of age of drinking onset and lifetime psychological distress. White lesbians, younger lesbians, and those with lower levels of education were at greatest risk of psychological distress. Conclusion: While the cross-sectional design precludes causal conclusions, study findings--especially those related to CSA--are consistent with previous research on predominantly heterosexual women in the general population. Lesbians who experienced CSA were at heightened risk of lifetime alcohol abuse and those who experienced CPA were at heightened risk of lifetime psychological distress relative to lesbians without abuse histories. Given the dearth of research on childhood abuse and sexual orientation, studies are needed that examine the similarities and differences between lesbians' and heterosexual women's experiences of, and responses to, childhood abuse.

Tetrad tests are a valuable tool for testing covariance structures, particularly when other tests such as the likelihood ratio test are not appropriate. However the implementation of tetrad tests is complicated by the fact that there are often multiple sets of nonredundant vanishing tetrads, and also by computational limitations, particularly for bootstrap tetrad tests for models with a large number of indicator variables. We show that a simple modification of a bootstrap tetrad test can overcome these limitations. Another beneficial result of this modification is that it can increase the power of the test.