Measures of Central Tendency - Averages Flashcards
How do you do a mean average?
Add all data and divide by number of data
Strength of a mean average
It uses all of the data points so provides a good estimate for the central score of a data set (wholly representative)
2 weaknesses of a mean average
- The mean is easily skewed by extreme values -anomalies
2. It cannot be used if the dataset is split into categories (non-numerical)
What is a median average?
Middle value when data is in numerical order
Strength of Median
Not affected by extreme values (weakness of mean)
Weakness of median
Not all values are used to calculate it, so the median may misrepresent data (strength of the mean)
What is the Modal Average?
Frequently occurring score
- there can be more than one mode if they occur frequently but generally a maximum of 2
- If every number appears equally (or 3+) there is no mode at all
Strength of the mode
It is the only measure of central tendency that can be used on nominal* data
*non-numerical
2 Weaknesses of the mode
- It can be unrepresentative - doesn’t always mean you can interpret your results
- It is of limited value when there are several or no modes
What is the scientific phrasing of the range?
Measure of dispersion
What does the range do?
Show how data is spread out
What are the two types of dispersion?
range and standard deviation
What is the significance of the range?
It gives us an indication of reliability:
Small range = consistent data set = increased reliability of data
What is standard deviation?
Shows the average distance of the mean of all data points, it is a measurement of variation
3 Strengths of standard deviation
Not distorted by anomalies
More accurate than a range
Allows us to see reliability of a data set (smaller standard deviation, more reliable the result)
