Descriptive Statistics Flashcards
measures of central tendencies
how close to the average values are
- mean, median, and mode
measures of dispersion
how far apart different values are
- range and standard deviation
what are nominal measurements?
most basic level, obtains info on frequency (based on named categories)
what are ordinal measurements?
- data that can be ranked in a logical order
- intervals aren’t standardised/ fixed e.g. rating scales and grade boundary differences
what are interval measurements?
- data that can be ranked with fixed intervals e.g. numerical scores, time, money, temperature
mean evaluation
most sensitive measure as it take into account all values, can be easily distorted by extreme values and therefore become unrepresentative
median evaluation
not affected by extreme scores/not as sensitive as only the middle values are reflected do can be easier to calculate than the mean
mode evaluation
unaffected by extreme values, not useful for explaining data when there’s more than one mode
range evaluation
affected by extreme values, fails to take into account the distribution of values
standard deviation evaluation
precise measure which takes into account all values, may hide characteristics like extreme values
what is the distribution of data?
when displaying the results of any research from a sample, they will usually follow a particular pattern, this can be normal, or positively or negatively skewed
how is the sample reflected by the distribution?
- skewed distribution: biased, small, and/or unrepresentative sample
- normal distribution: what you get/expect if your sample is representative, and/or large
when should the mean be used?
with internal data, although not with extreme scores (median)
- measure of dispersion: standard deviation
when should the median be used?
with ordinal data, or internal data with extreme values
- measure of dispersion: range
when should the mode be used?
with nominal data (data in categories)
