Paper 1 - Data/statistics Flashcards
what are measures of central tendency ?
averages of the data
mean, median and mode.
what are the advantages and disadvantages of mean ?
- it is affected by outliers.
- it uses every value in the data, so represents the data well.
what are the advantages and disadvantages of median ?
- less effected by outliers.
- does not account for the distance between values.
what are the advantages and disadvantages and mode ?
- can be used for nominal and ordinal data.
- when there is more than one mode it does not reflect the centre of data well.
what are measures of dispersion ?
the spread of data
range, variance and standard deviation
what are the advantages and disadvantages of range ?
- easy to calculate
- effected by extreme values
what is variance ?
measurement of the spread between numbers in a data set.
standard deviation squared
what is standard deviation
the square root of variance
how dispersed the data is from the mean
what are the advantages and disadvantages of variance and standard deviation
- all values are taken into account
- complex to calculate
what do bar charts represent ?
nominal data
what do histograms represent ?
continuous data
what to line graphs represent ?
continuous data
what do pie charts represent ?
nominal data
what do scatter graphs represent
correlational data
what does ∝ mean
proportional to
what are inferential statistics ?
procedures for drawing logical conclusions about the target population that the sample was drawn from.
what’s the observed value ?
the value produces after applying an inferential test formula.
what’s probability ?
the measure of the likelihood that an event may occur.
what is the significance level ?
the level of probability at which it has been agreed to reject the null hypothesis. 0.05.
what’s a type one error ?
when the researcher rejects the null hypothesis that is true.
what’s a type two error ?
when the researcher accepts a null hypothesis which is not true.
What’s quantitative data and its advantages/disadvantages ?
Data in numbers.
-Its easier to analyse because data is numerical which can be summarised using descriptive statistics (averages and graphs). This makes it easier to draw conclusions from the study as the data is represented clearly.
-It oversimplifies reality and human experience as it suggests that there are simple answers.
What’s qualitative data and its advantages/disadvantages ?
Non numerical data, e.g. pictures or words.
-Represents the true complexities of human behaviour because they’re not reduces to numbers.
-Provides rich detail of how people think and behave. This increases validity.
-More difficult to detect patterns and draw conclusions from because of the large variety of information collected.
What are the 3 levels of data and what do they mean ?
nominal- categories
ordinal - ranked
interval - public units of measurements
what does a small standard deviation mean ?
scores are close to the mean
what does a large standard deviation mean ?
scored are far from the mean - lots of individual differences
What are the steps for the wilcoxon test ?
- calculate the difference between each pair of scores. if the difference is zero ignore it in ranking.
- rank the differences from low to high ignoring negatives.
- add up the ranks for positive differences. then for the negative differences.
- chose the smallest value (observed value).
- compare it to the critical value table and write the significance statement.
in the wilcoxon test, does the observed value need to be lower or higher than the critical value ?
equal to or lower than.
