Distancia-Covid Survey: First Report

Introduction

This report provides preliminary results from the Distancia-Covid Survey launched on 14 May 2020 under the CSIC-funded project “Impacto de las medidas de distanciamiento social sobre la expansión de la epidemia de Covid-19 en España”. It relies on the survey responses received from the launch date through 10 June 2020. This period encompasses the vast majority of the responses received to date, and it corresponds to the time during which Spain was transitioning away from the extensive restrictions on mobility and social contacts that had been put into place with the state of alarm decreed on 14 March 2020. The state of alarm lasted until 21 June 2020 and Spanish territories were moving, at varying rates, through the three phases of the de-escalation process during the survey period analyzed here.

Survey Design

The survey was designed by the Distancia-Covid team in order to better understand changing patterns of human mobility and social contacts in Spain in the context of the Covid-19 pandemic. Many of the questions draw on the approach taken by the POLYMOD study (Mossong et al. 2008; Prem, Cook, and Jit 2017), and were developed in coordination with researchers in other countries working on similar surveys related to social mixing (Del Fava et al. 2020; Feehan and Mahmud 2020; Perrotta et al. 2020).

The survey was distributed in Spanish, Catalan, Galician, Basque, and English using Kobo Toolbox¹. Respondents accessed the survey at https://distancia-covid.csic.es/encuesta and it remains available at present at that URL. Respondents are able to access the survey questions only if they first provide informed consent.

The sampling design was non-random, based entirely on people self-selecting into the respondent pool by connecting to the survey URL online. The survey URL was distributed through press releases, Twitter, Whatsapp, and other channels by members of the project team and institutional press offices, and it appears to have propagated through digital networks reasonably well, reaching all provinces in Spain and a relatively wide segment of the population (see further below).

As of 10 June 2020 there were 4390 valid submissions. Initial data cleaning was done to improve the interpretability of variable names and generate additional variables calculated from the original ones. Among other things, an imputed usual postal code variable was created based on the two postal code questions in the survey, which asked respondents to list their current and usual postal codes. The imputed variable takes the value of the usual postal code when this has been provided. When it has not been provided it takes the value of the current postal code on the assumption that these are the same in these cases. In addition, province variables were created based on the first two digits of the postal code responses.

Descriptive Statistics

This section provides descriptive statistics of the 4390 survey submissions received as of 10 June 2020.

Temporal Distribution

Most survey submissions were made soon after the survey was released. Figure 1 shows the submission time pattern on a histogram with the data aggregated in 1-hour bins. As can be seen, there were several waves of submissions, with the largest occurring on the day the survey was released and then a later, much smaller wave on 25 and 26 May. There is also a clear daily cycle of submissions, which drop off at night (as one would expect).

Figure 1: Histogram of survey start times binned by the hour.

Geographic Distribution

Based on the imputed usual postal code variable, survey respondents appear to have had their usual places of residence distributed across Spain, with at least one respondent in each province. (This mostly also corresponded to their current places of residence, although 382 respondents listed different current and usual postal codes, and of these, 203 are in different provinces.)

In absolute terms, most respondents reported their usual places of residence in Madrid or Barcelona, as shown in the right panel of Figure 2. Relative to the province residential populations (taken from the padron), the greatest sampling fraction is from Girona, followed by Toledo, Bizkaia, Barcelona, and Castellon, as shown in the left panel of Figure 2.