Stats Flashcards
Why do we use stats test
To determine whether a difference or correlation is due to chance or significant
Define null hypothesis
No correlation or difference
Define significance level
Probability of being due to chance
What probability Is used in biology
0.05
When using measured data what stats test(s) may be used
Student t test
Correlation coefficint
How do you choose what type of stats to choose
Measured data or frequency in categories
What stats test is used when frequency is recorded
Chi squared test
What is the difference between correlation coefficient and student t test
Student t test = compare two means
Correlation coefficient = compare correlation between two variables
What is the minimum number of subjects in each group in student t tests
15
How do you calculate the degrees of freedom for student t test
(n1–1)+(n2–1)
n= number of subjects in group
What does 1, - 1 and 0 signify in terms of correlation coefficient
1= perfect +ve
-1= perfect - ve
0= none
How do you calculate the degrees of freedom in correlation coefficient
Number of pairs of measurements
How do you calculate to correlation coefficient for chi squared test
N–1
How do interpret a test statistic
Compare test statistic to critical value
Accept or reject the null hypothesis
State the probability that the difference is due to chance
Make a biological conclusion in context
When do reject the null hypothesis
When the test statistic is > the critical value
