statistical tests Flashcards
What are the three types of statistical tests
chi-squared
student T test
the correlation coefficient
what does chi-squared measure
it counts the frequency/how many individuals are in a category.
It investigates a difference between the observed unexpected numbers
What does it mean if the chi squared value is greater than the critical value
if the calculated value is greater than the critical value, that is a less than 5% probability that the difference between the observed and expected values is due to chance. This means that we reject the null hypothesis that there is a significant difference between the number of x variable and y variable.
What happens if the probability value is equal to the critical value in the chi squared
We reject the null hypothesis as there is a 5% probability that the difference in results is due to chance
How are biology statistical test different to maths statistical tests
In biology if the calculator value is greater than the critical value we reject the null hypothesis whereas in maths it’s the opposite
How do you workout the degrees of freedom in chi squared
you have the number of variables take away one
What is the student T test and what does it test for
Tests for continuous data (taking measurements) it investigates a difference between two means
How do you workout the degrees of freedom in a student T test
(The number of data points in the first sample + the number of data points in the second sample) -2
What is an unpaired student T test
Wehere both sets of data are independent and come from different individuals
What is a paired student T test
we are both sets of data come from the same individual or group.
but the sets of data can be collected at different times
Both groups have the same sample size
What happens if the student t-test value is greater than the critical value
H0: there is no significant difference between the mean of one set of data and another
We reject the null hypothesis above. There is a less than 5% probability that the difference between the means is due to chance, therefore we reject the null hypothesis.
What is the correlation coefficient and what does it test for
it tests continuous data, taking measurements/looking for an association/correlation between two measurements
What numbers can the correlation coefficient be between
-1 & 1
What does a positive value indicate in the correlation coefficient
Positive value indicates a positive correlation
What does a negative value represent in the correlation coefficient
A negative value represents a negative correlation
What does a value close to 0 represent in the correlation coefficient
A value close to 0 indicates little correlation between the two sets of data. Or it could indicate no correlation
What is another name that can be given to the correlation coefficient
The spearman’s rank correlation coefficient
What happens if the Spearman’s rank correlation coefficient is less than the critical value
H0: There will be no significant correlation between temperature and enzyme rate of reaction
There is a greater than 5% probability that the correlation is due to chance. Therefore we accept the null hypothesis. and increasing the temperature does not always result in an increase in the rate of enzyme reaction
What is a good way to remember whether a statistical test a significant or not
Pogba‘s left leg can shoot
PL LC S
if the probability/p value is less than the significance level then there is a less than (5%) probability that the difference in the two means is due to chance. this means that the difference between the two means is significant.
