When using the subtractive method, experimental manipulations are ...

[DelorasTo]

When using the subtractive method, experimental manipulations are used to
 
  a. alter the quality of stages involved in a task.
  b. alter the duration of stages.
  c. alter the error rates.
  d. add or delete stages.

Question 2

Last year, the state increased the speed limit on one section of highway from 55 to 65 mph. To evaluate the effect of the change, a researcher gathered accident reports for six months before the change and for six months after the change. This is an example of a(n) ____.
 
  a. time-series design
 b. interrupted time-series design
  c. cross-sectional design
 d. longitudinal design

[ktidd]

Answer to Question 1

D

Answer to Question 2

b

[DelorasTo]

Thanks for the timely response, appreciate it

[brbarasa]

Wow, this really help