Reading Quiz 1

Question 1

Distribution

Answer 1

Distribution of a variable indicates what values a variable takes n and the frequency at which it takes on these values

Question 2

Key features of a histogram

Answer 2

Center, spread, shape, outliers

Question 3

Three basic shapes

Answer 3

Symmetric, skewed right, skewed left

Question 4

Shape of distribution can also be described

Answer 4

By referring to number of modes

Uniondale, bimodal, multimodal, or uniform

Question 5

Measures of center

Answer 5

Mean and median

Question 6

Sample mean

Answer 6

Arithmetic average or arithmetic mean, average of a set of data values

Question 7

Median

Answer 7

Middle number

Question 8

Median position formula

Answer 8

Indicates where the median will lie
(n+1)/2
n = number of numbers in the data set
Formula only indicates where median is not what median is

Question 9

Perfectly symmetric vs skewed

Answer 9

If perfectly symmetric, mean equals median

If skewed, mean farther out in long tail than median

Question 10

Measures of spread

Answer 10

Range, interquartile range, five number summary, variance and sample standard deviation

Question 11

Range

Answer 11

Largest number minus smallest number

Question 12

Interquartile range

Answer 12

Q3 - Q1

Question 13

Five number summary

Answer 13

Minimum, Q1, median, Q3, maximum

Question 14

Most commonly used measure of spread

Answer 14

Standard deviation

Question 15

Variance

Answer 15

s^2 = (Σ(x1 - xbar)^2)/(n-1)

Question 16

Standard deviation

Answer 16

The square root of the variance, represented by s
Measures how the numbers are spread out from the mean
s = square root of variance formula
Nonresistant

Question 17

Deviation of xi from the mean

Answer 17

xi - xbar

Sum of all deviations of the mean equals zero

Question 18

Degrees of freedom

Answer 18

Quantity n - 1

Appears in the denominator of the formulas for variance and standard deviation

Question 19

Symmetric measures

Answer 19

Mean and standard deviation

Question 20

Skewed sets measures

Answer 20

Median and five number summary

Question 21

Outlier

Answer 21

An individual observation that falls outside the overall pattern of the graph
striking deviations

Question 22

Outlier test

Answer 22

Data point is outlier if it lies more than 1.5 interquartile ranges below Q1 or above Q3

Question 23

two types of graphs most appropriate for categorical data

Answer 23

pie charts and bar graphs

Question 24

graph inappropriate for when several percentages don’t represent portions of same whole

Answer 24

pie chart

Question 25

want raw data values, center, shape, spread, too many for dot plot, what graph

Answer 25

stemplot

Question 26

histogram

Answer 26

``` breaks the range of values of a variable into classes and displays only the count or percent of the observations that fall into each class most common graph of distribution of quantitative variable ```

Question 27

ogive

Answer 27

relative cumulative frequency graph horizontal axis: values of variable vertical axis: relative cumulative frequency

Question 28

how to find center of ogive

Answer 28

horizontal line from 50% on vertical axis to graph, that value is the center

Question 29

time plot axes

Answer 29

time is on horizontal axis

Question 30

trend

Answer 30

on time plot, overall upward or downward slope

Question 31

seasonal variation

Answer 31

time plot, shorter-term, regularly occurring, rise and fall variations

Question 32

resistant measure

Answer 32

measure of center of spread is relatively unaffected by extreme observations

Question 33

two resistant measures

Answer 33

median and interquartile range

Question 34

first quartile

Answer 34

the median of the subset of observations whose position in the ordered list is to the left of the overall median

Question 35

graph that gives picture of five number summary

Answer 35

boxplot

Question 36

IQR

Answer 36

Q3-Q1

Question 37

difference between regular and modified boxplot

Answer 37

regular is graph of five number summary | modified plots suspected outliers individually

Question 38

measures of spread

Answer 38

standard deviation and IQR

Question 39

when is standard deviation 0

Answer 39

when there is no spread aka all observations are the same value

Question 40

adding same number to each distribution

Answer 40

adds a to measures of center and to quartiles but does not change measures of spread

Question 41

multiply each observation by same number

Answer 41

multiplies both measures of center (mean and median) and measures of spread (IQR and standard deviation) by b

Question 42

three graphical measures of comparing distributions

Answer 42

bar charts, back to back stemplots, and side by side boxplots

Question 43

categorical variables

Answer 43

place individuals into groups or categories (qualitative)

Question 44

quantitative variables

Answer 44

numeric measures, makes sense to perform arithmetic operations such as adding or averaging

Question 45

most appropriate displays of categorical data

Answer 45

pie charts dot plots bar graphs

Question 46

best displays for quantitative data

Answer 46

dot plots stem plots histograms

Question 47

bins

Answer 47

values in piles, histograms, need to be physically and numerically equal in width

Question 48

rule of thumb bin number

Answer 48

square root of number of observations

Question 49

spread

Answer 49

level of variability, range also a measure of this

Question 50

standard deviation

Answer 50

measure of average distance of all observations from the mean

Question 51

box plots

Answer 51

not ideal indicators of shape and should not be used if there are other options