The example below demonstrates a mathematical model in a research.

In the model, $x_u$ represented a vector of the focal variables, including the level of cognitive $($vs$.$ affective$)$ appeal used in consumer i$\text{'}$s themail subject line $($EmailSubjectAppeal $t),$ consumer is tier $($Tier$,)$ and distance to the next tier goal $($GoalDistance$,)$ at the time of the themail, and their respective interactions. All the focal variables were mean$-$centered. $Z_t,$ was a vector of message content$-$ and timing$-$related control variables as described in the previous section. $C_{2,}$ represented a vector of consumer$-$related controls that included consumer demographics, program history, and previous email history as discussed in the last section. Finally, $,$

True

False