Tables And Graphs Flashcards
Why do scientists use graphs
- visualise patterns
- presentations, limited time
What are the two kinds of categorical data
- nominal
- ordinal (ordered eg 1st, 2nd)
What are the graphs used for categorical data
- bar charts
- bars shouldn’t touch, usually
How do stacked bar charts work
Categories within categories, can display either counts or percentages, if %, must add to 100
How do you make a pie charts
Convert to percentage, multiply by 360
What are the limitations of pie charts
- not good if you have lots of categories
- can be confusing to compare outcomes of 2 diff experiments
What are the two types of continuous data
Ratio or interval, data has standard units or a percentage
What is a histogram
- bars joined, because categories are continuous
- bar height represents frequency or %
- bar width represents width of a category
What are error bars on a histogram and what do they tell us
Vertical lines, show error rate, above and below bar height or line height
What is standard error
SD / square root n
When are scatterplots used
- two continuous variables
What is a positive and negative correlation on a graph
Positive = slants up
Negative slants down
Gradient = strength of correction
