When do you fail to reject the null hypothesis?

Wirth's mistake was in

a. generalizing too much from the urban conditions of the time in which he lived. b. underestimating the popularity of the suburbs. c. failing to identify the exurbs. d. not understanding the complexities of urban life.

A ___________ is a multi-item measure in which respondents are presented with increasingly difficult measures of approval for an attitude

a. Summation index b. Likert scale c. Guttman scale d. Factor analysis