Block 2

Question 1

attribute data?

Answer 1

discrete integers, a quantity

Question 2

types of data collection?

Answer 2

• direct observations (needed for quality calcs)

- questions (market research)

Question 3

Types of data?

Answer 3

-attribute data

variable data

Question 4

Variable data?

Answer 4

continuous values

Question 5

precision?

Answer 5

how reproducible a value is

Question 6

accuracy?

Answer 6

how close to the true value it is

Question 7

ways to describe data?

Answer 7

• frequency distribution
• measures of central tendency
• measures of dispersion

Question 8

Ways to sort data?

Answer 8

• categorically (eg.blood type)

- grouped (eg. 1

Question 9

relative frequency?

Answer 9

Out of 1, the proportion of the data in the specific group/value

Question 10

types of histogram?

Answer 10

• frequency histogram
• relative frequency histogram
• cumulative frequency histogram
• relative cumulative frequency histogram

Question 11

determining class width?

Answer 11

range/number of classes

Question 12

determining the number of cells in a histogram?

Answer 12

<100 →5-9 cells
100-500 → 8-17 cells
>500 → 15-20 cells

Question 13

Graphs for distribution?

Answer 13

• histogram
• bar graph
• polygon of data
• cumulative frequency distribution

Question 14

distribution graph with mean closer to the left?

Answer 14

skewed right / positively skewed (more values right of the mean)

Question 15

two peaks?

Answer 15

bimodal

Question 16

high peak/kurtosis?

Answer 16

leptokurtic

Question 17

low peak/kurtosis?

Answer 17

Platykurtic

Question 18

negative kurtosis?

Answer 18

flatter than a normal distribution with same mean and standard deviation

Question 19

aspects of a distribution?

Answer 19

• location (mean)
• spread
• shape (skew)

Question 20

3 measures of central tendency?

Answer 20

• Average
• Median
• Mode

Question 21

average of ungrouped data?

Answer 21

The mean

Question 22

average of grouped data?

Answer 22

sum of (frequency*midpoint) / total frequency

Question 23

average with different sized groups?

Answer 23

weighted average
sum of (frequency*average of each group) / total frequency

Question 24

Finding the median value for grouped data

Answer 24

• half the range
• count up to find the group
• find how many values intro the group it is
• divide by the group frequency and multiply by the group interval

Question 25

Mode?

Answer 25

peak | can have many or none

Question 26

Measures of dispersion?

Answer 26

- range - standard variation - variance

Question 27

Range?

Answer 27

difference between max and min in the dataset

Question 28

Standard deviation?

Answer 28

sum of differences between value (Xi) and average (Xbar) squared, divided by number of values (n) -1, square rooted

Question 29

Problems with range?

Answer 29

less accurate with more observed values, more likely to get an outlier

Question 30

When to use standard deviation?

Answer 30

went n>10 | otherwise, use range

Question 31

Measures of distribution shape?

Answer 31

- skewness - Kurtosis - Coefficient of Variation

Question 32

Skewness?

Answer 32

a3=0 →symmetrical a3>0 skewed to the right a3<0 skewed to the left +1 or -1 is big

Question 33

How to determine if a skewness value is reliable?

Answer 33

n>100 | needs to be unimodal

Question 34

What does Kurtosis value (a4) mean?

Answer 34

a4=3 → normal distribution a4>3 → more peaked a4<3 → less peaked

Question 35

Correlation variation / Coefficient of Variation

Answer 35

``` standard deviation (s) *100%/average (Xbar) units for s and the mean cancel, thus the units are % ```

Question 36

Coefficient of Variation vs standard variation?

Answer 36

relative to the mean - more relevant

Question 37

population?

Answer 37

set of items of interest

Question 38

Sample?

Answer 38

subset of a population

Question 39

sample statistics?

Answer 39

- Average (Xbar) | - Sample standard deviation (s)

Question 40

population parameter?

Answer 40

- Mean (Xbar0 or lowercase mu) | - Standard deviation (So or lowercase sigma

Question 41

statistic vs parameter?

Answer 41

statistic for a sample | parameter for a population

Question 42

average and standard distribution of standard normal curve?

Answer 42

``` average (mu) = 0 standard distribution (sigma) = 1 ```

Question 43

finding the percentage above/below a value on a normal curve?

Answer 43

transfer to standard normal distribution then use the tables

Question 44

How check for a normal distribution?

Answer 44

- visual inspection of a histogram (unimodal, symmetrical, tapering tails) - skewness = 0 - Kurtosis = 3

Question 45

Probability plots?

Answer 45

- order values small to large (and rank from 1 for smallest) - use plotting position equation to find percentile - plot measured value over percentile and draw line of best fit

Question 46

Chi-square goodness of fit?

Answer 46

-compares observed value to expected value

Question 47

Tests for normality?

Answer 47

- probability plots | - chi-square goodness of fit

Question 48

simplest way to find a cause and effect relationship?

Answer 48

scatter diagram

Question 49

drawing a "straight line fit" mathmatically?

Answer 49

use equations for find gradient (m) and y intercept (a)

Question 50

coefficient of correlation?

Answer 50

``` goodness of fit to a line of best bit. between -1&1 1=all points on +gradient line -1=all points on -gradient line 0=no correlation ```