Guys, lets say that I am conducting a study to find out the likelihood of students' overestimating the time required to get ready in the morning.

I have 100 students, and I get them to (1) self-report how long they took on Monday, and (2) gave them a device to measure how long they took on Tuesday. So two sources of info: self-report and by device.

I am supposed to use (2 methods of) inferential statistics to draw conclusions to my study (ps: the answer is that humans do indeed tend to over report).

which tailed test am I supposed to use? One or two? And what else can I use?