Lecture 3: Describing Data

Question 1

Mean

Answer 1

Sum of all values/Number of values

Question 2

Median

Answer 2

Middle value after sorting

Question 3

Mode

Answer 3

Most frequently occurring value

Question 4

Range

Answer 4

Maximum - Minimum

Question 5

Standard deviation

Answer 5

Average difference between average and the mean OR how spread out the values are

Question 6

Outlier

Answer 6

A value that isn’t near any other value in the list

Question 7

Why do outliers occur? (3 examples)

Answer 7

1. Incorrect value (misrecoreded/subject misunderstood)
2. Correct value but its natural variation
3. Correct value but subject is from different population than main population of interest

Question 8

What should we do with an incorrect value?

Answer 8

1. Correct the value if possible
2. If correction isn’t possible, remove value from the data set

Question 9

What should we do if its a correct value (natural variation)

Answer 9

We would keep the value, but note it’s presence in the report

Question 10

What do we with a correct value but the subject is from a different population than the main population of interest?

Answer 10

We would remove the value if the population it comes from isn’t the population of interest

Question 11

Whenever we remove a value what should we do in the analyses

Answer 11

Report it! It’s a part of being honest and complete in our scientific reporting

Question 12

Which is more sensitive to outliers between the mean or the median?

Answer 12

The MEAN! The median would be the same if any of the adjacent values changed