Week 2- Normal distribution and confidence intervals Flashcards
What is a confidence interval?
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)
How does confidence intervals help us infer differences in the means of measurements?
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.
What is the confidence level?
Confidence level is related to the amount of error we are willing to accept when calculating the range of the population mean.
What happens to the confidence interval when we increase the confidence level?
It increases in size
What is the margin of error?
It’s half of the confidence interval (the top and bottom half from the point estimate)
What is the point estimate?
The sample mean
What is the normal distribution?
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.
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?
In the normal distribution, the mean = median = mode. Therefore, the median and mode are 170.6cm.
What happens to the t-distribution as you increase the degrees of freedom?
It gets thinner
How many observations do we expect to have one SD away from the mean in normally distributed data?
Around 68% of all observations sit one SD away from the mean
