A3 Statistics Flashcards
What is standard deviation?
The spread of data around the mean
What does it mean If there is a larger standard deviation and what is it called?
There is more variation , it is called hetrogenuous
What does it mean if there is a smaller standard devation and what is it called?
There is less variation, it is called homogenuous
If error bars overlap what can we infer?
There is no significant difference in results
When comparing variation in size between two groups of organisms, it is often considered more useful to compare standard deviations rather than ranges. Explain why.
- Range can be influenced by a single outlier
- Standard deviation shows spread about the mean
- Range only shows highest and lowest values
What are the three Inferential Statistical tests?
Chi squared test , Spearman’s rank test and students t test
What is the defintion of a null hypothesis?
There is no relationship between 2 variables (due to chance maybe)
When is Chi squared used what does it do?
Used when data is categorical, it looks for differences between observed and expected data
What is an example of hypothesis that you would use Chi squared?
Do different species prefer different habitat
When is Spearman’s rank used and what does it do?
Used when examining an association between two sets of data
What is an example of a hypothesis where you would use Spearman’s rank?
How does a length of a snake affect a snake’s body mass
When is students t-test used and what does it do?
Used when comparing the mean values of two sets of data
What is an example of a hypothesis where you would use students t test?
Is there a difference in the mean mass of two different populations of gorilla
What does it mean if the probablity is greater than 5 percent?
- The results are due to chance so we accept null hypothesis
