Exploring DATA with graphs Flashcards
What 7 properties does a good graph have?
- Shows the data
- Induce the reader to think about the presented data
- Avoid distorting data
- Present many numbers with minimum risk
- Make large data sets coherent
- Encourage the reader to compare different pieces of data
- Reveal the underlying message of the data
Name 4 graph building guidelines
- If plotting two variables, never use 3D plots
- Do not use unnecessary patterns in the bars
- Do not use cylinder shaped bars if it is not functional
- Properly label the x and y axis
Name and describe the four types of histograms
- Simple histogram: visualise frequencies of scores for a single variable
- Stacked histograms: compare relative frequencies of scores across groups
- Frequency polygon: The same as a simple histogram, but uses a line, instead of a bar
- Population pyramid: Comparing distributions across groups and the relative frequencies of scores in two populations
What is a box plot? give another name for it?
A box-plot or box-whisker diagram uses the median as the centre of the plot. It is surrounded by the quartiles which show 25% and 75% of the data.
Name the three types of box plot diagrams
- 1-D boxplot- simple box plot for all scores of the chosen outcome
- Simple boxplot- multiple boxplots for the chosen outcome by splitting the data by a categorical variable
- Clustered boxplot- A simple boxplot, but it splits the data by a second categorical variable
Do bar charts often utilise the mean, median or mode?
Mean
What eight different types of bar charts are there?
- The means of scores across different groups or categories
- Clustered bar chart- Different coloured bars to represent levels of a second grouping variable
- Stacked bar- clustered bar, but the bars are stacked
- Simple 3-D bar-Second grouping variable is represented by an additional axis
- Clustered 3-D bar- a clustered bar, but an extra categorical variable can be added on an extra axis
- Stacked 3-D bar- a 3-D clustered bar, but the bars are stacked
- A simple error bar- a simple bar chart, but there is no bar, but a line and dot
- clustered error bar- clustered bar chart, but a dot with an error band around it
What are line charts?
Bar charts with lines instead of bars
What two types of line charts are there?
- Simple line- the means of scores across different groups of cases
- Multiple lines- This is equivalent to the clustered bar chart
What is meant by a scatterplot
A graph that plots each person’s score on one variable against their score on another
What 8 types of scatter plot are there?
- Simple scatter- A scatterplot of one continuous variable against another
- Groups scatter- Display points belonging to different groups in different colours
- Simple 3-D scatter- a scatterplot of one continuous variables against two others
- Grouped 3-D scatter- A scatterplot of one continuous variable against two others but displays different groups in different colours
- Summary point plot- A bar chart, but there is a dot instead of a bar
- Simple dot plot- A histogram, but instead of a summary bar representing frequency scores, individual scores are represented as dots
- Scatterplot matrix- A grid of scatterplots showing the relationship between multiple pairs of variables in each cell of the grid
- Drop-line- A clustered bar chart but a dot represents a summary statistic instead of a bar and a line connects the summary of each group
How is an outlier decided in a box plot?
Any score greater than the upper quartile plus 1.5x the IQR
How does spss mark an extreme score and an outlier in box plots?
circle- outlier
Asterix- extreme score
