Chapter 2 Measures Of Location And Spread - Year 1

Question 1

What may make the data’s 90 percentile un calculable?

Answer 1

Where P90 would be there is an open bounded group

Question 2

How do you work out the range in a frequency table with groups?

Answer 2

You take the extreme ends

Question 3

What does this mean?

Answer 3

X bar
This stands for the mean

Question 4

What does this mean?

Answer 4

The “sum of” all values of x

Question 5

What are the measures of spread?

Answer 5

Range
Standard deviation
Interquartile range
Variance

Question 6

What are the measures of location?

Answer 6

Maximum
Minimum
Quartiles
Percentiles
Deciles
-Median (the last 3 are measures of central tendency)
-Mode
-Mean

Question 7

What are then measures of central tendency?

Answer 7

Median
Mode
Mean

Question 8

Define measures of location

Answer 8

Single values which describe a position in a data set

Question 9

Define measures of central tendency?

Answer 9

Measures of location which are to do with the centre of the data

Question 10

Define measures of spread?

Answer 10

To do with how data is spread out

Question 11

How so you calculate the mean?

Answer 11

Write out the formular
Substitute the numbers in
State the answer

Question 12

How do you use your calculator to work out the mean of ungrouped data?

Answer 12

Press menu
Press 6 (statistics)
Press 1 (1 - variable)
Enter the data
Press AC
Press options
Press 2 (1 variable calc)

Write down the formular
Enter the numbers in
Then state the answer

Question 13

On your calculator, how do you turn on the frequency bit of the table?

Answer 13

Press:
Shift - menu setup
Down arrow
3 statistics
1 on

Question 14

How do you use your calculator to calculate the mean easily of grouped data (data with inequalities)?

Answer 14

You take the midpoint of each group and then use that as your frequency
Menu - 6
Enter the data
Press AC
Press options
Press 2

Write down the formular
Enter the numbers in
Then state the answer

Question 15

What is the mode?

Answer 15

The most frequent piece of data

Question 16

What is the median?

Answer 16

The middle piece of data once the data has been ordered chronological

Question 17

How do you calculate the median of ungrouped data?

Answer 17

(n+1) ÷ 2

Question 18

How do you find the median of listed data if the answer is in the middle?

Answer 18

You take the midpoint of the 2 values

Question 19

How do you find the position of median in grouped data?

Answer 19

Just n/2

Not (n+1) ÷2

Question 20

How do you use interpolation to work out the value of the median?

Answer 20

Find the sum of the frequency and ÷ 2. Then find which class your value lies in
Then draw the grid below and substitute your values into the equation a/b=c/d. Solve for c and then add it to the starting width of the class.

Question 21

Why may linear interpolation be inaccurate?

Answer 21

We assume that all data is evenly distributed within each group

Question 22

What do we need to do to make this work?
Why won’t it work in its current form?

Answer 22

There are gaps in the data. Therefore we need to convert them into an inequality.
It won’t work as data such as 9.9 isn’t included in these groups.

Question 23

How do you find the quartiles in a list or ungrouped data?

Answer 23

Find the median. Then split the data in 2 parts where you find the median in each but separately
(n+1) ÷ 2

Question 24

What do you need to use to work out the Quartiles in grouped data?

Answer 24

Interpolation

Question 25

How do you work out the IQR?

Answer 25

Q3-Q1

Question 26

Why might we use the IQR instead of the range? Disadvantages? How could you fix this?

Answer 26

We get to miss any extreme data at each end if the data However, we are discounting a lot of data that may be representable To fix this problem you could calculate an interpercentile range

Question 27

Give an example of a percentile?

Answer 27

Question 28

Give an example of a decile?

Answer 28

Question 29

Give an example of an interpercentile range?

Answer 29

Question 30

How do you convert percentiles to deciles?

Answer 30

÷10

Question 31

How do you convert deciles into percentiles

Answer 31

X10

Question 32

What may you need to use to work out a percentile?

Answer 32

Interpolation

Question 33

What does this mean:

Answer 33

The 90th percentile (or the 9th decile) It wants the 90th % of data.

Question 34

How do you calculate which value of the data a percentile wants?

Answer 34

You ÷ the number on the percentile by 100 (to get the number which you would multiply by if it was a %) Then do the sum of frequency X that number

Question 35

How do you work out the value of the data the decile wants?

Answer 35

You ÷ the number on the decile by 10 (to get the number which you would multiply by if it was a %) Then do the sum of frequency X that number

Question 36

What is variance?

Answer 36

A measure of spread that takes all values into account. By definition it is the average squared distance from the mean.

Question 37

What is the symbol for variance?

Answer 37

Question 38

What is the formular for variance?

Answer 38

Question 39

What is the symbol for standard deviation?

Answer 39

Question 40

What is the formular for standard deviation?

Answer 40

Question 41

How do you work out variance and standard deviation on a calculator?

Answer 41

Press Menu 6 1 Fill in the data AC Options 2

Question 42

Why may we code?

Answer 42

To make our data easier to use

Question 43

Explain how the code x=(y+10)will effect: The mean, SD and the variance?

Answer 43

Mean - increase by 10 SD won't change Variance

Question 44

Explain how the code x=(3y) will effect: The mean, SD and the variance?

Answer 44

Mean - 3 times bigger SD - 3 times bigger Variance

Question 45

Explain how the code x=(2y-10) will effect: The mean, SD and the variance?

Answer 45

Mean - 2 times bigger then 10 smaller Standard deviation - 2 times bigger only Variance

Question 46

You may be asked to decode a question once given the code. How do you do this?

Answer 46

Work out the answer in a coded answer Then but that answer into the formular (usually as equals to) Then solve it. Keep in mind what effects the mean, variance, Standard deviation

Question 47

When is the only time what letter is used matter in this topic?

Answer 47

Coding

Question 48

What may a question be asking you if it gives you these 2 values? What is the common mistake?

Answer 48

The standard deviation You may square the Σx^2 term although it is already squared