chapter 4: statistics Flashcards
what does statistics allow us to do
1, accept conclusions
2. reject conclusions
what is the mean
the average
what is the standard deviation
measures how closely the data are clustered around the mean
what does a small standard deviation mean
the more closely it is clustered around the mean
what is precision
reproducibility
what is accuracy
the nearness to the truth
experiments with a small SD are more…
precise
greater precision does not mean
greater accuracy
what form should you express the mean and SD
mean +-standard deviation(n=)
what is special about the average and the SD
they should end in the same decimal place
how do you find the degrees of freedom
n-1
what is variance
the square of the standard deviation
what is the relative standard deviation
standard deviatin expressed as a percentage of the mean
what is the equation for relative SD
s/x x100
what is the equation for the gaussian curve
what happens as an experiment is repeated more times
the results approaches an ideal gaussian curve
if there is an infinite set of data what happens to the mean and the standard deviation
it becomes (U symbol)
it becomes the circle symbol
what is the equation for a z score
what does the area under the curve add up to
1
what happens if there is a larger standard deviation
the broader curve
what is the equation of the standard deviation of the mean
standard deviation/ square root (# number of measurements)
what is the null hypothesis
states that two sets of data are drawn from populations with the same properties
when will we reject a null hypothesis
if there is less than 5% probability of observing the results
what tests do we use for a null hypothesis
- f test
- f test
what does the f test compare, what does the t test compare
- standard deviation
- the mean
what is the formula for f test
(s1)^2/(S2)^2
- put the larger SD on top so the numerator is more than 1
-Fcalc> Ftable = reject, difference is significant
what is the equation to calculate confidence intervals
mean +- ts/square root n
