Research Methods - Descriptive statistics

Question 1

What is central tendency?

Answer 1

A way to describe the center of a data set

Question 2

What are the three measures of central tendency?

Answer 2

1. mean
2. median
3. mode

Question 3

How do you calculate the mean?

Answer 3

add up all the data

divide by how many numbers there are

Question 4

Evaluate the use of mean:

Answer 4

Advantage = 1. it uses all the data, unlike range 2. can be used for continuous and discrete data
Disadvantage = 1. influenced by outliers an skewed distributions 2. cannot be used on nominal data

Question 5

How do you calculate the median?

Answer 5

put all the data in size order ad find the central point

Question 6

Evaluate the use of median:

Answer 6

Advantage = 1. gives a whole number to represent a set of whole numbers, rather than the mean which has 'spurious accuracy' so more representative 2. less influenced by outliers and skewed data 3. used when distribution is not symmetrical 
Disadvantage = 1. cannot be used for nominal data as it cannot be logically ordered

Question 7

How do you calculate the mode?

Answer 7

most common data

Question 8

Evaluate the use of mode:

Answer 8

Advantage = 1. can be used for both interval and nominal data (numerical and categorical and qualitative data)
Disadvantage = 1. not useful when items are different in the set 2. doesn't always represent center of distribution

Question 9

What is the measure of dispersion?

Answer 9

the measure of how stretched out or squeezed data is

Question 10

What are the three measures of dispersion?

Answer 10

1. range
2. variance
3. standard deviation

Question 11

How do you work out the range?

Answer 11

subtract the smallest data from the largest data

Question 12

What is variance?

Answer 12

A measurement of how spread out the data is

Question 13

What does a variance of 0 indicate?

Answer 13

That the values are identical

Question 14

What does a small variance indicate?

Answer 14

The data is close to the mean and near each other

Question 15

What does a high variance indicate?

Answer 15

The data is spread out around the mean and away from each other

Question 16

How do you work out variance?

Answer 16

1. work out the mean
2. for each ppt subtract the mean from their score to get (d) difference
3. square (d)
4. find the mean of the differences squared

Question 17

What is standard deviation?

Answer 17

a measure of dispersion which includes the square root of the variance

Question 18

What is the relevance of standard deviation to the variance?

Answer 18

Standard deviation is directly related to variance and is its square root

Question 19

How do you calculate standard deviation?

Answer 19

1. work out the mean
2. for each ppt subtract the mean from their score to get the difference (d)
3. square the difference (d)
4. find the mean of the differences squared
5. find the square root

Question 20

What is 1 standard deviation?

Answer 20

68% of values are within 1 standard deviation - 34% above and below the mean

Question 21

What is 2 standard deviations?

Answer 21

95% of values are within 2 standard deviations - 47.5% above and below the mean

Question 22

What is 3 standard deviations?

Answer 22

99.7% of values are within 3 standard deviations - 49.85% above and below the mean