4.3.1 Classification and Evolution – Statistical Analysis Flashcards
(15 cards)
Why do we use statistical tests?
It can help to determine whether a difference that is observed is a significant difference or simply natural variation (chance).
What is the formula for Standard deviation?
What is the standard deviation?
It is a measure of variation. It measures the amount of variation of spread from the mean.
What does a low standard deviation indicate?
That the observed data has a narrow range and the points are closely grouped to the mean. The data will therefore be reliable.
What is this the formula for Paired t-test?
What is a null hypothesis?
A prediction that there is no statistically significant difference between the means of two sets of data.
What is the purpose of a student’s t-test?
It is used to compare two means to test whether there is a significant difference between them.
How do we determine whether our results of a t-test are significant?
We check our t-value against a table of t-values assigned at the 5% significance level based on the degrees of freedom for the data.
What does x̅ represent in equations?
The mean of a set of data.
A t-value that is greater than the 5% value indicates what?
That there is a significant difference between the two data sets at the 95% confidence limits.
If we had a t-value greater than the 5% value would we reject or accept the null hypothesis?
We would reject the null hypothesis.
What is the spearman rank correlation coefficient used for?
It is used to consider the relationship between two sets of data and whether they are correlated.
What is this the formula for Spearman’s rank?
What does the term ‘degrees of freedom’ mean?
The number of values in a calculation which are free to vary.
If you have ten results for each of two data sets what is the number of degrees of freedom?
(n1+n2) – 2 = 18
