Maths/skills/stats Flashcards
How do you make a ratio x:1?
Divide first number by second number = x
What is the formula for calculating % change?
(difference/original) x 100
What is the formula for finding the unknown value for glucose concentration?
C1 x V1 (stock) = C2 x V2 (known)
C = concentration
V = volume
What is the formula for calculating Rf value?
distance travelled by solute/distance travelled by solvent
How is ratio converted to a percentage?
e.g. x:1
(x/1) x 100
What is standard deviation?
A measure of the spread of the data around the mean value
What does it mean if there is an overlap in standard deviations?
It is likely there is no significant difference
Why are small samples bad with standard deviation?
Aren’t representative or reliable
How do you calculate rate?
change in y/change in x
When is students T-test used?
When finding the difference between two mean values
When is correlation co-efficient used?
Looking for an association between x and y
When is the Chi squared test used?
When comparing frequencies within categories
What should you include in Evaluate questions?
- No stats test done?
- Small sample size?
- Only focuses on one thing? (e.g. question asks about cancer but data only provides information on LUNG cancer)
- Only starts to be a difference after a certain point? (e.g. drug only starts to have an effect after 5 arbitrary units)
How do you calculate pH when given the concentration of H+ ions?
-log[H+]
How do you calculate concentration of H+ when given the pH value?
10^(-pH)