Slow algorithms: More calculations

- [Instructor] The second reason…that some algorithms are much slower than others…is some algorithms just perform more calculations.…Let's take a look.…This is an artificial neural network…that's been built on the same data set.…All we're trying to do is predict whether…or not an expectant mom will have a low birth weight baby.…Now, artificial neural networks get quite technical,…but take a look.…I just want you to attend to the very large number…of lines.…If we were using a statistically-based approach,…we've only got three variables here,…weight of the mom, uterine irritability, and hypertension.…

A statistical approach would only do four calculations,…one per variable and what's called the constant,…but the point is there would only be four.…But look at all these lines, many, many more,…so the neural net is doing many more calculations.…That makes it more accurate, but it makes it slower.…Over here, we've got six times five lines,…and yes, indeed, there's a relationship between the number…of shapes on the left and the number…