Though the northernmost islands experience a bit of rain, September is largely dry, warm and sunny throughout the islands. High season in Hawaii doesn't start till mid-December, so September is still off-season for the Hawaii tourism industry and deals abound.
T-tests and analysis of variance (ANOVA) are widely used statistical methods to compare group means. For example, the independent sample t-test enables you to compare annual personal income between rural and urban areas and examine the difference in the grade point average (GPA) between male and female students.
Significance tests (such as the t test or ANOVA) provide a way to decide whether an effect exists, but do not provide a clear indication of how large an effect is. Measures of effect size provide an indication of the size of an effect (strength of the IV) and, therefore, provide important additional information.