Descriptive Statistics

Question 1

What are descriptive statistics

Answer 1

The use of graphs, tables and summary statistics to identify trends and analyse sets of data

Question 2

What are measures of central tendency and three examples

Answer 2

Averages which give information about the most typical values in a set of data eg mean,median and mode

Question 3

How is the mean calculated

Answer 3

By adding up all the values in a data set and dividing this by the total number of values there are

Question 4

Advantages of the mean

Answer 4

Most sensitive value as includes all values in the data set within the calculation, means it is representative of the data as a whole

Question 5

Limitations of the mean

Answer 5

Easily distorted by extreme values

Question 6

What is the median

Answer 6

Middle value in a data set when scores are arranged from lowest to highest

Question 7

Advantages of the median

Answer 7

-extreme values do not distort it
-easy to calculate

Question 8

Limitations of the median

Answer 8

Less sensitive than mean as not all scores are included in the final calculation

Question 9

What is the mode

Answer 9

The most frequently occurring value within a data set, can be two modes(bi-modal) or no mode

Question 10

Advantages of the mode

Answer 10

-very easy to calculate
-for data in categories it is the only method you can use

Question 11

Limitations of the mode

Answer 11

-may not be representative of data as a whole as does not take into account all values

Question 12

What are measures of dispersion and two examples

Answer 12

Based on the spread of scores which is how far scores vary and differ from one another eg range and standard variation

Question 13

What is the range

Answer 13

Worked out by taking the lowest value from the highest and usually adding 1 which accounts for margins of error

Question 14

Advantage of the range

Answer 14

Easy to calculate

Question 15

Limitations of range

Answer 15

Only takes into account the two most extreme value meaning the range may be unrepresentative of the data set as a whole

Question 16

What is standard deviation

Answer 16

Single value that tells us how far scores deviate from the mean, larger the SD=greater the dispersion

Question 17

What do large and low standard deviations mean for an experiment

Answer 17

-large standard deviation suggests not all participants were affected by the IV in the same way, may be anomalous results
-low standard deviation reflects fact that the data is tightly clustered around the mean, all pps responded in a similar way

Question 18

How to calculate standard deviation

Answer 18

Calculate the difference between the mean and each score and add up all the differences and divide this by the number of scores, standard deviation is the square root of the variance

Question 19

Advantages of standard deviation

Answer 19

More precise measure of dispersion than range as includes all values within the final calculation

Question 20

Limitations of standard deviation

Answer 20

Can be distorted by a single extreme value as it includes all values