Measures of Central Tendency & Dispersion

Question 1

What exactly are measures of central tendancy?

Answer 1

• Known as descriptive statistics- measures averages which gives us info about most typical values in a set of data

Question 2

What are the 3 types of measures of central tendancy?

Answer 2

• Mean
• Median
• Mode

Question 3

What is the mean the median & the mode?

Answer 3

• Mean: The arithmetic average calculated by adding up all of the values in a set of data & dividing by number of values
• Median:The central value in a set of data when values are are arranged from lowest to highest
• Mode: The most frequently occuring value in a set of data

Question 4

What are the two measures of dispersion?

Answer 4

• Range
• Standard Deviation

Question 5

What is the range?

Answer 5

• Worked out by taking the lowest value from the highest value
  (you usually add 1) once you get your answer

Question 6

What is the standard deviation?

Answer 6

• Tells us how much on average, each score deviates from the mean
• The larger the standard deviation the larger the greater the dispersion or spread within a data set
• A large standard deviation suggests that not all ppts were affected by the IV in the same way because data is spread
• Low standard deviation reflects data is tightly clustered around the mean which might imply that all ppts responded in a fairly similar way

Question 7

What are the benefits & drawbacks of standard deviation?

Answer 7

Benefits:
- SD is a much more precise measure of dispersion than the range as it includes all values within final calculation

Drawbacks:
- However, for this reason- like the mean it can be distorted by a single extreme value
- Extreme values may not be revealed, unlike w the range.