Chapter 3

Question 1

Define: mean

Answer 1

Total of all values divided by number of values

Symbol: µ (population), X with overline (sample)

Question 2

Define: median

Answer 2

The midpoint of a distribution; the number such that half of the values are above and half are below
Symbol: M

Question 3

Mean vs median:

Answer 3

Mean is drawn toward outliers and skew; median is resistant

Question 4

Define: mode

Answer 4

The value that occurs with highest frequency in a data set

Question 5

Advantages and disadvantages of mode:

Answer 5

Pro: can be used in qualitative analysis
Con: may or may not exist, there may be more than one

Question 6

Define: standard deviation

Answer 6

How closely values are clustered around the mean

Question 7

For a symmetric distribution with one peak, the values of mean, median, and mode are:

Answer 7

Identical and at the centre of the distribution

Question 8

For a right-skewed distribution, values of mean, median, and mode are:

Answer 8

Mean is largest, mode is smallest, and the value of the median is between them. Opposite for left-skewed.

Question 9

Small SD means:

Answer 9

Values are spread over a relatively small range around the mean

Question 10

Formulas for variance and SD for ungrouped data

Answer 10

*** slide 7

Question 11

Variance and deviation are represented by:

Answer 11

Population - sigma

Sample - s

Question 12

Define: population parameter or just parameter

Answer 12

A numerical measure (ex: mean, median, mode, variance, SD) calculated for a data set

Question 13

Can SD be negative?

Answer 13

nope. only zero or positive.

Question 14

Define: statistic

Answer 14

A summary measure calculated for a simple data set

Question 15

Shortcut formulas for variance and SD for ungrouped data:

Answer 15

*** slide 7

Question 16

Formulas for grouped data:

Answer 16

*** slide 10

Question 17

Chebyshev’s theorem:

Answer 17

For any number k greater than 1, at least (1 - 1/k^2) of the data values lie within k standard deviations of the mean.

Question 18

Empirical rule: For symmetric and bell-shaped distributions, __% of values lie within __ standard deviations of the mean.

Answer 18

68%, 1 SD
95%, 2 SD
99.7%, 3 SD

Question 19

Quartiles:

Answer 19

Quartiles divide the dataset into 4 equal parts. Values below the first quartile are the lower quarter. The second quartile is the median. Values above the third quartile are the upper quarter.

Question 20

Define: interquartile range

Answer 20

The difference between the first and third quartiles

Question 21

Five-number summary:

Answer 21

Min, Q1, Q2, Q3, max

Question 22

Box and whisker plot shit: