For sampling, an open, public communication campaign was run through direct emailing by the project team on the basis of the national registry of industrial firms (API), a sponsored Facebook/Linkedin campaign, and official political partner institutions websites and email lists. Interested SMEs could sign up through the website of the program through a short registration form. In total, 266 SMEs signed up after two month of communication between December 2020 and January 2021, among which 214 complied with the eligibility criteria (6-200 employers, industrial activity, exporting or intention to export in the future, not being part of a foreign multinational company).
Among the eligible firms, 107 firms were allocated to a treatment and 107 firms to a control group on June 8th 2021. The randomisation was stratified based on four sectoral groups and the certification status of the company. In four strata we further subdivided into smaller strata if there were sufficient observations and high variation in the percentage of sales firms’ realised with exports. Given the relatively small sample size, we also re-randomised based on the rule that none of 7 baselines covariates (e.g. number of export countries, total export sales in Tunisian Dinar in 2020 etc.) were independently or jointly significantly different for treatment and control group( “big stick” method as documented in Mckenzie and Bruhn 2009, Morgan and Rubin 2012, Soares and Wu 1983).
The allocation of firms in the treatment and control group was announced at registration for the program and communicated publicly on the program's website to ensure transparency and equality of opportunity. The randomisation was done by the researchers in Stata, recorded and made public on the project’s website.