AFM 112 - Chp 3

Question 1

Define a frequency table

Answer 1

number of observations in each class/category/data
define a relative frequency table

Question 2

define a relative frequency table

Answer 2

percentage of observations that fall in each class/category (frequency/total number of observations)

Question 3

when to use a bar graph vs pie chart

Answer 3

bar graphs uses a bar to represent each category + height of the bar equal to the frequency or relative frequency of the class/category (more specific)

pie chart - each class/category is represented by a slice and the size of each slice is proportional to the relative frequency of the class/category (more general)

Question 4

What do we use to summarize + describe quantitative data

Answer 4

measures of central tendency + measures of variability of dispersion

Question 5

define measures of central tendency

Answer 5

capture the tendency of the data to cluster around some central values

Question 6

define measure of variability

Answer 6

captures the spread of data

Question 7

what’s the use of a histogram in graphing?

Answer 7

to capture the shape of distribution

Question 8

what are the histogram distributions described as? and define them

Answer 8

1. symmetric - looks the same on both sides from the centre
2. skewed left - majority of the data is on the right but there is a little bit of data on the left
3. skewed right - majority of the data is on the left but there is a little bit of data on the right

4.bimodal - 2 spikes

5.multimodal - multiple spikes

Question 9

how do we use mean + median to predict the shape of distribution

Answer 9

1. if mean = median, distribution = likely symmetric
2. if mean > median, distribution = likely skewed to the right - if difference is significant, it indicates there’s are outliers at the upper end (right side)
3. if mean < median, distribution = likely skewed to the left. if the difference is significant, there are outliers at the lower end (left side)

Question 10

define the interquartile range

Answer 10

distance between the first and third quartile

Question 11

what’s the spreadsheet formula for first and third quartile?

Answer 11

1st quartile =percentile (e1:e39, 0.25)

3rd quartile = percentile (e1:e39, 0.75

Question 12

define variance

Answer 12

averaged squared deviation from the mean

Question 13

define standard deviation

Answer 13

square root of the variance - higher the value, higher the variability

Question 14

what are the 3 assumptions we can predict if the shape of distirbution is bell shaped and symmetric

Answer 14

1. 68% of the observations will fall within 1 standard deviation from the mean - (range = x-1s to x+1s)
2. 95% of the observations will fall within 2 standard deviation from the mean, (range = x-2s to x+2s)
3. 99.7% of the observations will fall within 3 standard deviation from the mean (range = x-3s to x+3s)

Question 15

What’s the importance of data understanding?

Answer 15

structure of the data + data captured in each variable

Question 16

define accuracy/consistency in terms of data quality

Answer 16

data set = accurate + consistent if it is as free as possible from intentional/unintentional errors

data values = accurate if they capture what the decision maker would consider as the actual value

data values = consistent if they do not change across occurrences

Question 17

Define timeliness in data quality context

Answer 17

if it contains info that is time relevant to the business problem that it will be used to address

Question 18

define completeness in terms of data quality

Answer 18

data set is complete if all the data points needed to capture a transaction are available

Question 19

define outliers + the importance

Answer 19

observations in a data set far away from the bulk of the observations

outliers are important as they may indicate various info - eg. potential fraud

Question 20

what’s the rule of distribution for detecting outliers in a bell shaped distribution

Answer 20

any value which is more than 3 standard deviation above the mean or below the mean.

Question 21

what’s the rule for detecting outliers in any distribution

Answer 21

any value which is above the end of the upper whisker (Q3 + 1.5*IQR) or is below the end of the lower whisker (Q1 - 1.5IQR)

Question 22

what are the 3 count functions in excel and the differences?

Answer 22

count - counts any cell with numerical data

count A - counts any cell with any data type

count blank - counts any cell with a blank value

Question 23

What are some issues with data quality?

Answer 23

missing values (using count functions), erroneous data

Question 24

what’s the function to categorize data?

Answer 24

unique function

Question 25

what’s the use and importance of filter function?

Answer 25

Filter (range, condition 1, [condition 2, etc])

Question 26

sort, filter, unique function

Question 27

clenaing data fucntions - time based - month, text functino, year function

Answer 27

“mmm”, “mmmm”, “ddd”, “dddd”

Question 28

What’s the spreadsheet formula to find the interquartile range?

Answer 28

v

Question 29

vlookup function

Question 30

sumif, countif, averageif function

Question 31

nested if functions

Question 32

round function

Question 33

text function

Question 34

datedif, today, now function

Question 35

proper, lower, upper, trim, concatenate function

Question 36

len, search, left, right, substitute function