Statista Data on topics such as advertising rates, magazine revenue, social media use, etc., and includes links to the issuing sources.
Interactive Advertising Bureau (IAB)
Pay-Per-Click ROI Calculator and E-Mail ROI Calculator from Entrepreur.com
MPA – The Association of Magazine Media Offers data by periodical title on advertising paging and expenditures, as well as research reports on readership, media effectiveness, audience behavior, etc. The MPA Magazine Media Factbook provides extensive data on the magazine industry, including readership demographics. The 2020 edition contains initial insights related to the COVID-19 pandemic.