HW3 CH2 - measure of center, variation, 5 # Sum, Box Plots

Question 1

Define the measure of center

Answer 1

Descriptive measure that reveals the center or most typical values of a data set

Question 2

What is a sample mean?

Answer 2

sum of all values divided by the total number of observations in the data set

Question 3

how do you obtain the sample mean?

Answer 3

add all the data and divide it by how much data there is

Question 4

what is the symbol for sample mean?

Answer 4

x with a line above it

Question 5

what is the symbol for population mean?

Answer 5

the u with a tail, “mu”

Question 6

what is a median?

Answer 6

A number that divides the top 50% of the data from the bottom 50%

Question 7

how do you find the median?

Answer 7

rearrange numbers from least to greatest, odd # is in the middle, even # is (add both middle #’s)/2

Question 8

what is mode?

Answer 8

the value that occurs the most often in the data set, frequency > 1

Question 9

Is it possible for a data set to have 2 or more mode? (T/F)

Answer 9

yes

Question 10

what is resistant measure?

Answer 10

a measure is robust (resistant) if extreme values have little to no influence on its outcome

Question 11

what is a robust measure, mean or median?

Answer 11

median

Question 12

What is measures of Variation (Dispersion)?

Answer 12

descriptive measures that describe how much variation or “spread” there is in a data set

Question 13

what is range?

Answer 13

The difference between the largest observation and the smallest observation

Question 14

what are the disadvantages of range?

Answer 14

1. measure is based only on 2 values
2. not resistant: highly susceptible to outliers

Question 15

what is deviation?

Answer 15

The difference between an observation and the mean

Question 16

what is a sample standard deviation?

Answer 16

Roughly on average, the difference between an observation and the mean

Question 17

Is range resistant?

Answer 17

no

Question 18

Does range show how spread out the data is?

Answer 18

Yes

Question 19

is standard deviation robust?

Answer 19

no

Question 20

Why transform data?

Answer 20

changing units, making the shape symmetric, make the relationship between 2 variables linear

Question 21

define parameter

Answer 21

numerical summary oof the population

Question 22

define statistic

Answer 22

numerical summary of the sample

Question 23

define quartiles

Answer 23

this divides the data set into 4 equal parts

Question 24

What is the interquartile range?

Answer 24

the difference between the third and the

Question 25

What is the 5 number summary?

Answer 25

is consists of the info: 1. minimum value 2. first quartile 3. second quartile (median) 4. third quartile 5. maximum value

Question 26

What is an outlier

Answer 26

A value that is distant from other observations in the data set

Question 27

define a boxplot

Answer 27

a graph that displays the distribution of a data set using the 5 number summary , which we can easily see the outliers

Question 28

what advantage does histogram have against boxplot?

Answer 28

displays more information about the distribution of a data set

Question 29

Define Dot plot

Answer 29

a graphical display of data using dots (dot = value in data set) limit value grouping

Question 30

define stem and leaf plot

Answer 30

a table in which each possible value is split into a "stem" (1st digit) and "leaf" (last digit)

Question 31

What are the advantages of stem leaf and dotplot?

Answer 31

displays all possible values in the data set

Question 32

what are the disadvantages in the stem leaf and dotplot?

Answer 32

When the data set is large this will not be informative, use a histogram instead

Question 33

what is a histogram?

Answer 33

a graph is drawn using vertical bars. bar height = frequency

Question 34

what does a frequency histogram

Question 35

what do outliers affect?

Answer 35

Mean and standard deviation (not resistant measures)

Question 36

what is the degrees of freedom?

Answer 36

n-1 of the sample variance

Question 37

Name the 4-step process to organize a statistical problem

Answer 37

state: what is the practical question? plan: what specific statistical operations does this problem call for? solve: analyze the data with graphs and computations conclude: give your practical conclusion

Question 38

The mean is a measure of center whereas the standard deviation measures the ____________ of data about the mean.

Answer 38

variability

Question 39

The line in the box of a boxplot marks where the __________ is.

Answer 39

median

Question 40

Standard Deviation measures...

Answer 40

variability of data about the mean or the difference between an observation and the mean

Question 41

what is deviation?

Answer 41

The difference between an observation and the mean xi - x

Question 42

how do you figure if a sample is an outlier?

Answer 42

if it is within the upper limit or the lower limit calculations (Q1+1.5 x IQR) and (Q3+1.5 x IQR)

Question 43

How do you find the interquartile range?

Answer 43

Q3 - Q1 = IQR