5 metrics you need to know to give a great presentation

1.5 seconds the amount of time you have to make a positive first impression. 
2.5 minutes the average audience attention span (down from 12, then 5 in past ten years)
150 average number of times the average American checks his/her phone in 24 hour period
12 maximum number of words that should be projected on your screen at a time
100 percent of your audience will appreciate your speech ending on time

via Noah Zandan, CEO of Quantified Impressions