presenting data Flashcards
when/how are bar charts used?
- represent different categories/group different scores of a group, e.g. a mean
- discrete data
rules when drawing a bar chart
- keep bars separate/not touching
- amounts on y-axis equal distances apart
- clear and operationalised labels
when/how are histograms used?
- data in quantities rather than categories
- represents data on a continuous scale
rules when drawing a histogram
- bars are touching
- y-axis must start at zero
- clear and operationalised labels
when/how are scatter graphs used?
- two co-variables on both the axis
- shows type of correlation between variables
rules when drawing a scatter graph
- a line of best fit
- axis don’t need to start at zero
- accurate plots
- clear labels
when/how are pie charts used?
- display data for a maximum of six categories
- often used to show percentages of a population, e.g. ethnicity
rules when drawing a pie chart
- percentages must add up to 100%
- angles in circle must add up to 360
- clear labels
- must include a key
when/how are line graphs used?
- represents continuous data
- shows trends overtime
- often used to compare two or more conditions simultaneously
rules when drawing a line graph
- clear labelling
- key if there are multiple conditions
- axis don’t need to start at zero
how to work out S.D.
- find the mean of the values
- subtract the mean from each individual value
- square the new values
- add all of the values together
- divide by n-1
- square root
(n is the number of ppts)
mean
add all the values together and divide by how many there are
median
the middle number. if two values are in the middle, the median is the middle of those two values
mode
the value that appears the most
level of significance
used in order to make safe predictions, 5% being due to chance is usually used in psychology
type 1 error
- a false positive
- accepting the alternative hypothesis when you should’ve accepted your null (too lenient)
type 2 error
- a false negative
- accepting the null hypothesis when you should’ve accepted your alternative (too strict)
nominal data
data is put into categories, ppts given the option of one or another, e.g. marital status.]
ordinal data
when data is ranked/ordered, e.g. service quality rating
interval data
difference between measurements (can go into minuses), e.g. temperature in fahrenheit
ratio
difference between measurements (cannot go below zero), e.g. age
Man Whitney test
test of difference, independent groups, ordinal data
Chi Squared test
test of difference, independent groups, nominal data
Wilcoxon test
test of difference, matched pairs/repeated measures, ordinal data
Spearmans Rho test
test of association or correlation, ordinal data
positive skew
- most scores on the left with a long tail on the right
- happens when a test is difficult so scores are lower
- mean ‘pulled’ right
negative skew
- most scores on the right with a long tail on the left
- happens when a test is easy so scores are higher
- mean ‘pulled’ left
