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Another estimating approach that you can use is a three point estimate.

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And there are a couple of variations of this she'll need to know for your exam.

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A three point estimate is where we find the average of the optimistic the most likely and the pessimistic

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this thing approached a three point estimating is called a triangular distribution because we have a

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triangle of optimistic most likely and pessimistic.

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So there you go triangle.

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So in this example if we had an optimistic estimate of 25 hours or most likely 45 or pessimistic the

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worst case is 75 so we took 25 plus 45 plus 75 and then divide by three.

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It would be forty eight point three three hours.

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So that's what we would predict how long that activity would take.

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Another approach is a perch technique it's also a three point estimate.

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And this is called beta distributions so it's a little different.

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Pert means program evaluation and review technique but we just call it what it does.

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It's weighted towards the most likely where the trained gular it was just an average person has a little

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little weight or weight it factor for most likely.

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So what we're doing here we take optimistic plus four times the most likely plus pessimistic divided

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by six and that will equal our estimate.

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So we'll take the same case here 25 45 and 75.

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So we take four times 45 plus 25 plus 75 or whatever that comes out to be.

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We divide by six and then we would say it's forty six point six six hours.

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We're weighted meaning that we're putting more belief in the most likely time.

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So this is called a beta distribution it's a beta of our X factor towards the middle.

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Beta distribution.

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3. estimates You might also see them abreviated like this on your exam.

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Don't let it worry you don't let it throw you where most likely might be a t in an optimistic t and

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no I'm pessimistic t it p.

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And then a three point estimate.

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A T.

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Uppercase e.

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And then you can see the little T there preceding all of our factors that just means time.

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So a little hint.

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You can also do this with cost.

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So instead of a T you might see a little scene there.

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And so the C would be it's a cost with a three point estimate.

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And we'll see that in chapter 7.

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Let's compare and contrast here.

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All right so we have an optimistic of 40 hours most likely 55 pessimistic at 70.

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So what happens if we do it with perked.

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And what will happen if we do it with our three point estimate.

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So what will the results be.

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So let's take a look at our formulas.

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So our total for the three point estimate if we take 40 plus 55 plus 90 is 185 divided by three 61 points

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point seven that's our average amount of time.

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That's what we would predict if we use pert.

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It's 40 plus 55 plus 90 and you could see our formula 40 plus four times 55 plus 90 divided by six.

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So you see some of those up divide by six.

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And the answer would be fifty eight point three.

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So what's happening here is with a three point it's just the average.

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So if you have a very negative pessimistic or a really aggressive optimistic estimate it will skew your

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average in per everything is skewed if you will or weighted towards most likely.

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So you have to have a lot of confidence in your most likely estimate.

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You do this for every single activity to do three point or per.

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The reality is you could take just some of your activities and do this.

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But for your exam it's used to the whole project.

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So that's pert and three point estimate.

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So know how to do those you're probably going to have to do that math on your exam.

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All right.

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Keep moving forward.

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I'll see you in the next lecture.