DECK 3

Question 1

What is a standard deviation?

Answer 1

average distance to the mean

Question 2

what is a z score?

Answer 2

the number of standard deviations away from the mean

Question 3

what is the empirical rule?

Answer 3

mean? 68-95-99.7 yeahh?..

Question 4

what are the percentiles from left to R

Answer 4

2.5-16-50-84-97.5

Question 5

what is the mean/median/mode helper diagram?

Answer 5

a skewed left distribution because the mean, median andmode are positioned in that order from L to R

Question 6

When can you round?

Answer 6

AT THE VERY END!!! (keep 3 sig digits until end!)

Question 7

Which is more sensitive to outliers and skewed?

Answer 7

Mean and SD are more influenced by outliers. median and IQR are RESISTANT, RESILIENT, ROBUST!!

Question 8

How many SD wide is the IQR in a normal distribution?

Answer 8

NOT 2!!!! The middle 68% is 2 sd wide, since the IQR is only the middlest 50%, it is less than 2?. try [invnorm(.75)] x2

Question 9

are any populations actually normal?

Answer 9

no, nothing is normal, just normalish. The only normal thing is the model we use.

Question 10

are there any normal samples?

Answer 10

no, nothing is normal, just normalish. The only normal thing is the model we use.

Question 11

How do you compare sprinters to pole vaulters?

Answer 11

Use their z scores

Question 12

Why do we use median and IQR with skewed data, or data with outliers?

Answer 12

The median and IQR are more resiliant. Imagine if the oldest person in your class was 18, and you mistakenly typed in the number 18,000,000,000,000 into a data set of the ages in your class instead of 18. This will really impact the mean and the st. dev. However, it will make almost change at all to the IQR or to the median.

Question 13

Why do we go out 1.5 IQR’s when making the outlier fences?

Answer 13

Because 2 is too far, and 1 isn’t far enough

Question 14

What is the big confusion between box plots and normal models?

Answer 14

A lot of students think that a z score of 1 is the same as Q3 and a z score of -1 is like Q1. THIS IS INCORRECT!!!! In the normal model, the middle part holds 68% of the data, in a box in whisker it only holds middle 50%. To get to Q3 and Q1 you have to go up and down about .67 st. devs.

Question 15

What is the z score for Q1 and Q3?

Answer 15

about -.675 and .675

Question 16

So… how many SD wide is the IQR?

Answer 16

1.35…. NOT 2!!! We only want the middle 50%… Go up and down .675 from the middle and get 1.35 standard deviations wide!!

Question 17

What is the flow chart?

Answer 17

Question 18

Draw and completely label a normal model

Answer 18