The phrase "survey period" refers to a specific timeframe during which data is collected by conducting a survey or asking people questions to gather information. Full definition
Canadian manufacturers indicated a modest reduction in their payroll numbers during the latest survey period, thereby continuing the trend seen throughout much of the year to date. (rbc.com)
Between 1999 and 2004, 1.4 percent of young children had elevated blood lead levels, the smallest percentage of any of the prior survey periods. (scientificamerican.com)
I do not expect to know if our request is granted until after the fall survey period ends. (tnedreport.com)