Descriptive statistics Flashcards
What are descriptive statistics?
descriptive statistics describe the data set created by an investigation e.g experiment
What does descriptive data sets focus on?
Quantitative data. They use methods that summarises and describes what the data is showing, allowing us to draw meaningful conclusions
What are measures of central tendency? and the 3 kinds?
Measures of central tendency inform us about central values for a set of data
The three measures of central tendency are mean, median and mode.
Evaluation of mean?
+ It is more representative of the data. Measure of central tendency as it includes all of the scores in the dataset within the calculation
- It can be distorted by extreme scores and in such cases become unrepresentative of all scores so it can be misleading
Evaluation of median
+ Extreme scores do not affect the median
- Not all scores are included so its not the most representative because the value of lower and higher numbers are ignored)
Evaluation of mode
+ Unaffected by extreme scores
+ For data in categories mode in the only method you can use
- Sometimes there is more than one mode or not one at all
- Not representative of the whole data, can be unreliable and give an inaccurate picture of the data set
What are measures of dispersion? and the two kinds
Measure of dispersion shows how spread out the scores are in a data set
The two measures of dispersion are:
- range
- standard deviation
Evaluation of range?
+ It is easy to calculate and takes into account of the full spread of data
- It is not appropriate to use when there are extreme scores as these can give a distorted picture.
What is standard deviation?
The standard deviation is a more precise measure of dispersion and it tells us how the scores are spread around the mean
In order to have standard deviation what must the data have?
The data must have a normal distribution - this is calculated using a formula. This is a single value that tells us how far scores deviate from the mean
What does a small standard deviation suggest?
That the data is closely clustered around the mean which implies that participants all responded in a fairly similar way
What does a large standard deviation suggest?
That the data is widely spread/dispersed around the mean which suggests that not all participants were affected by the IV in the same way because the data is widely spread.
Evaluation of standard deviation?
+ It is very precise as it gives an accurate measure of the spread of scores
+ not difficult to calculate
- It may hide some extreme values of the data set
