o1 o2 o3 x o4 o5 o6 -only one group -interested in how participants change -good if you're worried about history affects or maturation
o1 o2 o3 x o4 o5 o6 -only one group -interested in how participants change -good if you're worried about history affects or maturation
a time-ordered sequence of observations taken at regular intervals; data points indexed in time order for a one unit of observation (i.e.: single individual, etc.).