descriptive statistics Flashcards
what are the two types of descriptive statistics?
measures of central tendency
measures of dispersion
^ analyse data 2 help describe, show or summarise it in a meaningful way
what are measures of central tendency?
name the 3 measures of central tendency
- mode
- mean
- median
what is the mean?
and how do you calculate it?
- This is the arithmetic average of all scores
- It is calculated by adding up all the scores and dividing by the total number of scores
advantages and disadvantages of using the mean
- adv - can consider all results
- disadv - can be affected by anomalies
what is the median?
and how do you calculate it?
the mid point of a set of scores when they are placed in rank order
It is calculated by finding the middle score after placing all the scores in numerical order
advantages and disadvantages of using the median
- adv - Not affected by anomalies.
- disadv - doesn’t consider all the results in a set of data, may not accurately reflect it.
what is the mode?
and how do you calculate it?
the most frequently occurring score in a set of data
what are the advantages and disadvantages of using the mode?
adv - Considers all the results in a set of data, not effected by extreme scores
disadv - doesn’t consider all the results in a set of data, may not accurately reflect it
what is a measure of dispersion?
A measure of dispersion shows how far the scores are spread from the measure of central tendency
what is standard deviation?
shows how far the scores are spread from the measure of central tendency such as the mean
what is the range?
A measure of dispersion which shows the difference between the highest and the lowest scores in a data set
A high range value - scores are spread out
low range value - scores are close together
what is a weakness of using the range?
- Affected by extreme scores so may not be an accurate descriptive statistic if there are outliers.
- It doesn’t tell us if the scores are bunched around the mean score or equally distributed around the mean.
- If the a data set has outlying scores it is often better to calculate the standard deviation.
what are the strengths of using standard deviation?
all exact values are taken into account, so a precise measure of dispersion