Normal Distribution

Question 1

what is a symmetrical distribution?

Answer 1

a normal distribution, symmetrical bell shape, median and mean are same values

Question 2

what is a negative distribution?

Answer 2

negatively skewed, long tail is on the left side, mean < median on x-axis

Question 3

what is a positive distribution?

Answer 3

positively skewed, long tail is on the right side, mean > median on x-axis

Question 4

what is the empirical rule?

Answer 4

determines proportion of observations between mean and fixed units of standard deviations

Question 5

what percentage of observations fall within +/- 1 standard deviation from the mean in a normal distribution?

Answer 5

68%

Question 6

what percentage of observations fall within +/- 2 standard deviations from the mean in a normal distribution?

Answer 6

95%

Question 7

what percentage of observations fall within +/- 3 standard deviations from the mean in a normal distribution?

Answer 7

99%

Question 8

what is a z-score?

Answer 8

measures distance, in standard deviation units, of any value from the mean of the (norma) distribution