descriptive statistics

Question 1

measures of central tendency

Answer 1

inform us about central values for a set of data
average can be calculated in different ways, different situations

Question 2

how to calculate the mean?

Answer 2

add up data items and divide by number of data items

Question 3

advantages of mean

Answer 3

• representative of all data
• sensitive statistic - takes account of the exact distance between all values of all data

Question 4

disadvantages of mean

Answer 4

• cannot be used with nominal data
• anomalous values can distort and misrepresent data

Question 5

how to calculate median?

Answer 5

arrange in order of size and select the central value
even no. - calculate median value must add 2 median values and divide by 2

Question 6

advantages of median

Answer 6

• easy to calculate
• not distorted by anomalies
• not affected by extreme scores so can be useful under such circumstances

Question 7

disadvantages of median

Answer 7

• less sensitive than the mean because the exact values are not reflected

Question 8

how to calculate mode?

Answer 8

most common value

Question 9

advantages of mode

Answer 9

• unaffected by extreme values
• useful for discrete data
• can be used for nominal data

Question 10

disadvantages of mode

Answer 10

• mode may not represent data
• data cannot be described using this statistic

Question 11

measures of dispersion

Answer 11

finds how spread out data items are

Question 12

how is range calculated?

Answer 12

(biggest value - smallest value) +1

Question 13

advantages of range

Answer 13

• easy to calculate

Question 14

disadvantages of range

Answer 14

• effected by extreme values
• doesn’t take into account the distribution of numbers

Question 15

how is standard deviation calculated?

Answer 15

σ = √[(∑(d’)2 /n) - (∑d’/n)2] × i

Question 16

advantages of standard deviation

Answer 16

• precise measure of dispersion
• takes into account all values

Question 17

disadvantages of standard deviation

Answer 17

• may hide some characteristics of the data set