Week 2- Normal distribution and confidence intervals

Question 1

What is a confidence interval?

Answer 1

Confidence intervals show us the range of sample means we would expect to have if we collected samples of the same size and infinitum (infinity)

Question 2

How does confidence intervals help us infer differences in the means of measurements?

Answer 2

If we have two confidence intervals next to each other, we can check if there are significant differences between the two measurements simply by looking at whether the intervals overlap.

Question 3

What is the confidence level?

Answer 3

Confidence level is related to the amount of error we are willing to accept when calculating the range of the population mean.

Question 4

What happens to the confidence interval when we increase the confidence level?

Answer 4

It increases in size

Question 5

What is the margin of error?

Answer 5

It’s half of the confidence interval (the top and bottom half from the point estimate)

Question 6

What is the point estimate?

Answer 6

The sample mean

Question 7

What is the normal distribution?

Answer 7

It’s a bell-shaped distribution that often appears when we collect and plot data.

Things like heights and weights, for example, tend to follow the normal distribution.

Question 8

You collect 500 people’s heights and find that (a) your data follows the normal distribution, and (b) the mean height is 170.6cm. What is the median and mode?

Answer 8

In the normal distribution, the mean = median = mode. Therefore, the median and mode are 170.6cm.

Question 9

What happens to the t-distribution as you increase the degrees of freedom?

Answer 9

It gets thinner

Question 10

How many observations do we expect to have one SD away from the mean in normally distributed data?

Answer 10

Around 68% of all observations sit one SD away from the mean