Check whether the sample standard deviations for the data sets satisfy our criterion for the use of ANOVA to compare the population means. Do we need to proceed with caution in either case? (a1) Researchers compared forest plots in Borneo that had never been logged (Group 1) with similar plots nearby that had been logged one year earlier (Group 2) and eight years earlier (Group 3). Although the study was not an experiment, the authors explain why?