COVID-19-related knowledge, attitudes and practices: a mixed-mode cross-sectional survey in Liberia

ObjectivesTo examine the knowledge, attitudes and practices (KAP) of COVID-19 of rural and urban residents in Liberia to inform the development of local social and behaviour change communication strategies.DesignCross-sectional, mixed-mode (online and telephone) survey using non-probability sampling.SettingAll 15 counties in Liberia with a focus on Maryland County.ParticipantsFrom 28 May to 28 June 2020, data were collected from a total of 431 adults aged 18 years and older (telephone 288 (66.8%); online 143 (33.2%)) out of a total of 741 contacts.Main outcome measuresKAP scores. Frequencies and proportions were calculated, followed by univariate and multivariable analyses to examine the association between KAP scores and the sociodemographic variables.ResultsAround 69% of the online survey respondents were younger than 35 years of age, compared with 56% in the telephone interviews. The majority (87%) of online respondents had completed tertiary education, compared with 77% of the telephone respondents. Male participants, on average, achieved higher knowledge (52%) and attitude scores (72%), in contrast to females (49% and 67%, respectively). Radio (71%) was the most cited source for COVID-19 information, followed by social media (63%). After controlling for sociodemographic variables, adaptive regression modelling revealed that survey mode achieved 100% importance for predicting knowledge and practice levels with regard to COVID-19.ConclusionsThe survey population demonstrated moderate COVID-19 knowledge, with significant differences between survey mode and educational level. Correct knowledge of COVID-19 was associated with appropriate practices in Maryland County. Generalisation of survey findings must be drawn carefully owing to the limitations of the sampling methods. Yet, given the differences in knowledge gaps between survey modes, sex, education, occupation and place of residence, it is recommended that information is tailored to different audiences.

The Joint UAV-Borne Magnetic Detection System and Cart-Mounted Time Domain Electromagnetic System for UXO Detection

For unexploded O=ordnance (UXO) detection, individual technology cannot achieve the best detection performance. The new detection mode of joint magnetic and electromagnetic method has attracted more and more attention. In this paper, a newly developed joint detection system is introduced, a multi-rotor UAV-based magnetic system (UAVMAG) and a cart-based time-domain electromagnetic detection system (TDEM-Cart) are combined, and the cooperative processing of magnetic field and electromagnetic data is proposed. The result of the joint inversion fuses the feature vector retrieved from the magnetic field data and the feature vector inverted from the electromagnetic data, providing more accurate positioning results and richer information, which is favorable to locate and distinguish the UXO. Two field experiments are conducted, and the results show that when the joint system works in the full-coverage survey mode, both ferromagnetic and non-ferromagnetic metal targets can be detected, avoiding missed detections. In addition, when the joint system works in the cued survey mode, the detection efficiency is improved, the positioning accuracy of joint interpretation is less than 10 cm, and it shows satisfactory performance in the recognition of targets.

The effects of a special sequential mixed-mode design, and reminders, on panellists’ participation in a probability-based panel study

The sequential mixed-mode strategy has become standard practice in the survey management of longitudinal studies, in order to achieve consistently high response rates. To realise this aim in a cost-efficient way, a first mode is often an online questionnaire, towards which the target persons are pushed, and a second mode is then a telephone interview, offered to those who do not respond to the initial mode. However, the rationale for using the sequential mixed-mode plus “push-to-web” strategy to reduce the burden of choosing between survey modes, in order to maximise survey participation, could be undermined if there is an overlapping field period during which the target persons could choose between two or more offered modes. The use of reminders might be useful in solving this problem of competing risks. In the context of a multiple-panel study, this question was investigated by utilising longitudinal paradata from the fieldwork, as well as procedures of event history analysis that are adequate for the analysis of processes with competing risks. First, for a web survey as the initial mode and computer-assisted telephone interview (CATI) as the subsequent mode, it was found that the idea of a sequential mixed-mode plus “push-to-web” strategy does work even in the case of competing risks in the choice of a survey mode. Second, it was confirmed that reminders are a useful instrument for stimulating panellists to choose the running survey mode. Third, and finally, it was found that this feature of survey management is effective in countering panellists’ procrastination in regard to responding to a survey.

Survey Mode Effects on Objective and Subjective Questions: Evidence from the Labour Force Survey

Web questionnaires are increasingly used to complement traditional data collection in mixed mode surveys. However, the utilization of web data raises concerns whether web questionnaires lead to mode-specific measurement bias. We argue that the magnitude of measurement bias strongly depends on the content of a variable. Based on the Luxembourgish Labour Force Survey, we investigate differences between web and telephone data in terms of objective (i.e., Employment Status) and subjective (i.e., Wage Adequacy and Job Satisfaction) variables. To assess whether differences in outcome variables are caused by sample composition or mode-specific measurement bias, we apply a coarsened exact matching that approximates randomized experiments by reducing dissimilarities between web and telephone samples. We select matching variables with a combination of automatic variable selection via random forest and a literature-driven selection. The results show that objective variables are not affected by mode-specific measurement bias, but web participants report lower satisfaction-levels on subjective variables than telephone participants. Extensive supplementary analyses confirm our results. The present study supports the view that the impact of survey mode depends on the content of a survey and its variables.

Collecting the Data

This chapter discusses aspects related to data collection. It focuses, firstly, on sampling issues and, secondly, on the survey mode. Sampling issues include sample size and the type of sampling that enable precise estimates to be obtained. Regarding the survey mode, discrete choice experiments can be implemented by mail, telephone, face-to-face or web surveys. Each of these survey modes has its advantages and shortcomings. They are described and compared in the course of this chapter, addressing an important decision in the planning process of a discrete choice experiment.