Descriptive statistics

Question 1

What are descriptive statistics?

Answer 1

-Measures of central tendency- mean, median, mode
-Measure of dispersion- standard deviation, range

Question 2

What are measures of central tendency?

Answer 2

Typical value of a data set

Question 3

What are measures of dispersion?

Answer 3

-range
-Standard deviation

Question 4

What is the mean?

Answer 4

-Average which is calculated by adding all values together and dividing all the total by the number of scores
-Used with exact interval data

Question 5

What are strengths of the mean?

Answer 5

-Most sensitive measure of central tendency because individual values are used
-Most representative measure of central tendency because the whole data set is used
-This is why it is commonly used with interval data

Question 6

what are the limitations of the mean?

Answer 6

-can be misinterpreted if there are extreme high or low scores (outliers) in a data set
-If this is the case, the median should be used

Question 7

What is the median?

Answer 7

-The central value in a list of ranked values
-with an even number of values the median is the midpoint between the two values
-used with ordinal data (ranked data)

Question 8

what is the strength of the median?

Answer 8

-not affected by outliers, because it focuses on only the scores in the middle of the distribution
-therefore, it is better with skewed data than the mean

Question 9

What are the limitations of the media?

Answer 9

-not as sensitive as the mean-although the whole data set is used when ordering, not all individual values are used
-time consuming in large data set to organise a group of numbers in ascending order

Question 10

What is the mode?

Answer 10

-Most common value in a set of scores
-That may be two modes (bi-modal) -Or no mode, if all the scores are different
-Used nominal data (categoric data)

Question 11

what is the strength of the mode?

Answer 11

-useful when the data is in categories as it can be a more appropriate way of describing data compared to the mean
-e.g. when describing the avg number of children in a family in the UK, it is better to say the modal value of 2 rather than the mean of 2.334

Question 12

what are the limitations of the mode?

Answer 12

-not as sensitive as other measures- although the whole data set is used, no numerical values are used.
-not useful with several modes in a data set
-May not be representative of the data set if the most frequent item is extremely high or low

Question 13

what are the measures of dispersion?(spread of data)

Answer 13

-range
-Standard deviation

Question 14

What is the range?

Answer 14

calculated by taking away the lowest value from the highest value in a data

Question 15

What is the strength of the range?

Answer 15

-Quick and easy to calculate as it only uses the highest and lowest score in the data set compared to standard deviation which is more complex to calculate

Question 16

What are the limitations of the range?

Answer 16

-distorted by outliers because it only uses the lowest and the highest score in the data set
-does not show whether the data is evenly spread above and below the mean

Question 17

What is standard deviation?

Answer 17

-calculated by working out the average distance of each value from the mean

Question 18

What does a larger standard deviation indicate?

Answer 18

The values in a data set are more variable (less consistent) due to individual differences

Question 19

What are the strengths of standard deviation?

Answer 19

-more sensitive and precise than the range since all values are used in the calculation
-Allows for the interpretation of individual scores in relation to the standard deviation, when scores are normally distribute

Question 20

What are the limitations of standard deviation?

Answer 20

-more complicated and time consuming to calculate compared to the range
-As it uses the mean, it is distorted by extreme scores which make it less representative of the data set