Prevalence estimates for COVID-19-related health behaviors based on the cheating detection triangular model.

BACKGROUND: Survey studies in medical and health sciences predominantly apply a conventional direct questioning (DQ) format to gather private and highly personal information. If the topic under investigation is sensitive or even stigmatizing, such as COVID-19-related health behaviors and adherence to non-pharmaceutical interventions in general, DQ surveys can lead to nonresponse and untruthful answers due to the influence of social desirability bias (SDB). These effects seriously threaten the validity of the results obtained, potentially leading to distorted prevalence estimates for behaviors for which the prevalence in the population is unknown. While this issue cannot be completely avoided, indirect questioning techniques (IQTs) offer a means to mitigate the harmful influence of SDB by guaranteeing the confidentiality of individual responses. The present study aims at assessing the validity of a recently proposed IQT, the Cheating Detection Triangular Model (CDTRM), in estimating the prevalence of COVID-19-related health behaviors while accounting for cheaters who disregard the instructions. METHODS: In an online survey of 1,714 participants in Taiwan, we obtained CDTRM prevalence estimates via an Expectation-Maximization algorithm for three COVID-19-related health behaviors with different levels of sensitivity. The CDTRM estimates were compared to DQ estimates and to available official statistics provided by the Taiwan Centers for Disease Control. Additionally, the CDTRM allowed us to estimate the share of cheaters who disregarded the instructions and adjust the prevalence estimates for the COVID-19-related health behaviors accordingly. RESULTS: For a behavior with low sensitivity, CDTRM and DQ estimates were expectedly comparable and in line with official statistics. However, for behaviors with medium and high sensitivity, CDTRM estimates were higher and thus presumably more valid than DQ estimates. Analogously, the estimated cheating rate increased with higher sensitivity of the behavior under study. CONCLUSIONS: Our findings strongly support the assumption that the CDTRM successfully controlled for the validity-threatening influence of SDB in a survey on three COVID-19-related health behaviors. Consequently, the CDTRM appears to be a promising technique to increase estimation validity compared to conventional DQ for health-related behaviors, and sensitive attributes in general, for which a strong influence of SDB is to be expected.

Estimating the proportion of non-heterosexuals in Taiwan using Christofides' randomized response model: A comparison of different estimation methods.

In social research, investigating sensitive, highly personal or embarrassing issues by means of standard survey techniques based on direct questioning leads to refusals to answer or false responses which, generally, flaw the validity of the analyses and produce incorrect inferences. To correct biases induced by nonresponse or underreporting of sensitive matters, Warner (1965) introduced an indirect questioning approach, known as the randomized response technique, which allows researchers to estimate the proportion of individuals with sensitive attributes or behaviors, while ensuring respondents' privacy protection. In this article, we consider the randomized response model proposed by Christofides (2003) and, through a simulation and an empirical study, compare different estimation methods for the prevalence of a sensitive attribute. Specifically, we discuss how the model has been implemented in a pilot study to collect data and derive maximum likelihood and Bayesian estimates for the proportion of non-heterosexuals aged 20 years or older for the Taiwanese population and for some subgroups of it by sex and age. Our analysis, and in particular the Bayesian approach, seems to meet the expectation of social researchers and experts of sexual behaviors. In fact, the produced estimates are higher than official findings in Taiwan obtained by direct questioning in face-to-face interviews and provide a more reliable picture of sexual identity in the country. Moreover, Bayesian estimates appear more accurate than those produced by the method of moment and the maximum likelihood method.

Estimates of Lifetime Extradyadic Sex Using a Hybrid of Randomized Response Technique and Crosswise Design.

The prevalence of extradyadic sex (EDS) tends to be underestimated due to underreporting in national surveys, which use direct questioning. Self-administered questionnaires can reduce this response bias but may cause the anxiety of privacy exposure. Randomized Response Technique (RRT) can ensure participants' confidentiality under the randomized design of indirect questions to and was found to yield more valid estimates of sexual or other sensitive behaviors than direct questions. This study estimated the EDS rate among Taiwanese aged 18 years and over, using a hybrid of Randomized Response Technique and Crosswise Design (RRTCD) and the Weighted Conditional Likelihood (WCL) estimator. The data analyzed were from the 2012 Taiwan Social Change Survey, in which the answer to the innocuous question from the unrelated-question RRT of Greenberg, Abul-Ela, Simmons, and Horvitz (1969) was obtained indirectly from a demographic question related to the innocuous question. This RRTCD provided more information on the innocuous question to effectively improve the efficiency of the unrelated-question RRT of Greenberg et al. The WCL estimator was found to be more efficient than the Greenberg et al. estimator for estimating the EDS rate in terms of smaller standard errors and smaller differences in the levels of EDS across sociodemographics and extramarital-sex attitudes. Similar to those suggested in the literature, the estimated rates of EDS in two subsamples were higher among men, homosexuals, those who have or had wages, and those who accepted extramarital sex. The levels of EDS varying with sociodemographics were different between the married and the unmarried.

An alternative to unrelated randomized response techniques with logistic regression analysis.

The randomized response technique (RRT) is an important tool that is commonly used to protect a respondent's privacy and avoid biased answers in surveys on sensitive issues. In this work, we consider the joint use of the unrelated-question RRT of Greenberg et al. (J Am Stat Assoc 64:520-539, 1969) and the related-question RRT of Warner (J Am Stat Assoc 60:63-69, 1965) dealing with the issue of an innocuous question from the unrelated-question RRT. Unlike the existing unrelated-question RRT of Greenberg et al. (1969), the approach can provide more information on the innocuous question by using the related-question RRT of Warner (1965) to effectively improve the efficiency of the maximum likelihood estimator of Scheers and Dayton (J Am Stat Assoc 83:969-974, 1988). We can then estimate the prevalence of the sensitive characteristic by using logistic regression. In this new design, we propose the transformation method and provide large-sample properties. From the case of two survey studies, an extramarital relationship study and a cable TV study, we develop the joint conditional likelihood method. As part of this research, we conduct a simulation study of the relative efficiencies of the proposed methods. Furthermore, we use the two survey studies to compare the analysis results under different scenarios.

Semiparametric methods in the proportional odds model for ordinal response data with missing covariates.

We consider the estimation problem of a proportional odds model with missing covariates. Based on the validation and nonvalidation data sets, we propose a joint conditional method that is an extension of Wang et al. (2002, Statistica Sinica 12, 555-574). The proposed method is semiparametric since it requires neither an additional model for the missingness mechanism, nor the specification of the conditional distribution of missing covariates given observed variables. Under the assumption that the observed covariates and the surrogate variable are categorical, we derived the large sample property. The simulation studies show that in various situations, the joint conditional method is more efficient than the conditional estimation method and weighted method. We also use a real data set that came from a survey of cable TV satisfaction to illustrate the approaches.

Characterization of cyclodextrin glycosyltransferase of the same gene expressed from Bacillus macerans, Bacillus subtilis, and Escherichia coli.

The plasmid pHG contains a cyclodextrin glycosyltransferase (CGTase) gene (cgt) derived from Bacillus macerans. Two transformants, Bacillus subtilis (pHG) and Escherichia coli (pHG), were found to produce CGTases with the same primary structure as the enzyme from B. macerans. However, the beta-cyclodextrin coupling activity of the CGTase from E. coli (pHG) was 14-fold higher than that of the enzymes from the other strains. By contrast, no differences in alpha-cyclodextrin coupling activities were observed among these CGTases. CGTase from E. coli (pHG) was found to be less thermostable than the other CGTases. When the CGTase produced by B. subtilis was treated with increasing urea concentrations (10-1000 mM) to promote increasing degrees of protein unfolding, a bell-shaped beta-cyclodextrin coupling activity profile was obtained. Subtle differences in the conformation of the CGTase produced by E. coli are therefore proposed to be responsible for the markedly increased beta-cyclodextrin coupling activity of this enzyme.

Cranial-base morphology in children with class III malocclusion.

The association between cranial-base morphology and Class III malocclusion is not fully understood. The purpose of this study was to investigate the morphologic characteristics of the cranial base in children with Class III malocclusion. Lateral cephalograms from 100 children with Class III malocclusion were compared with those from 100 subjects with normal occlusion. Ten landmarks on the cranial base were identified and digitized. Cephalometric assessment using seven angular and 18 linear measurements was performed by univariate and multivariate analyses. The results revealed that the greatest between-group differences occurred in the posterior cranial-base region. It was concluded that shortening and angular bending of the cranial base, and a diminished angle between the cranial base and mandibular ramus, may lead to Class III malocclusion associated with Class III facial morphology. The association between cranial-base morphology and other types of malocclusion needs clarification. Further study of regional changes in the cranial base, with geometric morphometric analysis, is warranted.