Interviewing procedures
1.When is data collected for each wave of the study? 
The interview period (field season) is roughly between March and November, with a few years being exceptions and going into December. If a user is interested in when a specific interview was conducted, there is a variable in the dataset (Date of Interview) which indicates month and day of interview.
2.How often are main interview data collected for the PSID study? 
Between 1968 and 1997, data were collected every year. Starting in 1999, the PSID collected data biennially (i.e., every other year). All waves of data starting with 1968 are available on the website, with each wave's public release file being posted on the website as soon as editing and processing can be completed.