Measures of Location and Spread

Question 1

Measures of location

Answer 1

Specific values that describe a position in a data set

Question 2

Measures of central tendency

Answer 2

To do with the centre of data i.e average

Question 3

Measures of spread

Answer 3

About how data is spread out

Question 4

Setting the column for frequency on a calculator

Answer 4

On stat press F1, F2 1var freq and the column number

Question 5

Mean on calculator

Answer 5

Fill in the data on your table and press F1

Write values into ∑x/n

Question 6

Mean on grouped data

Answer 6

Set the value on each data to the midpoint

Question 7

Position of median in listed data

Answer 7

n/2
If decimal round up
If whole use halfway between that and the next value

Question 8

Median in grouped data

Answer 8

Use n/2 and use linear interpolation

Group is the first who’s first maximum CF is out of the range

Question 9

Linear interpolation median

Answer 9

Smallest value in section + (position-lowest position in group)/range of CFs in group * range of group

Question 10

Quartiles for listed data

Answer 10

n/4 or 3n/4 then round up if decimal and halfway between the item and the one after if whole

Question 11

Quartiles for grouped data

Answer 11

n/4 or 3n/4 then interpolate - don’t round

Question 12

Notation for LQ, median and UQ

Answer 12

Q1, Q2, Q3 (1,2,3 in subscipt)

Question 13

nth percentile notation

Answer 13

Pn(n in subscript)

Question 14

Percentiles of grouped data

Answer 14

Number of items * 0.percentile and interpolate - don’t round

Question 15

Variance

Answer 15

The average squared distance from the mean

Question 16

Variance formula

Answer 16

σ^2 = (Σx^2)/n - (Σx/n)^2

or Σx^2)/n - (mean x)^2

Question 17

Standard deviation formula

Answer 17

σ = sqrt(variance) = sqrt((Σx^2)/n - (Σx/n)^2)

Question 18

Coding y = ax+b to measures of location and standard deviation

Answer 18

measures of location: a(x value) + b

σ: a(x value)

Question 19

Coding variance

Answer 19

Code for standard deviation and square

Question 20

Reversing coding

Answer 20

Rearrange the coding formula for the original value and apply the rules