stats 1 Flashcards
why do we need statistics
all measurements we make are subject to variability
how are variations in measurements created
instrumentation (calibration, consistency)
experimenter (errors in reporting)
what causes biological variations
genetic differences
environmental differences
what is the mean
sum of all values/number of observations
what is the deviation
difference between each value and the average
what the variance
sum oaf all deviations squared/number of observations minus 1 (in sample)
average of the square of the deviations
what is the standard deviation
square root of variance
typical deviation
standard error of the mean
SD/root of n (number of observations)
error associated with the mean
population parameters
population mean: mew (u)
population variance: sigma squared
population standard deviation: sigma
what does the area under relative frequency histogram bars add up to
1
what percentage of a normal distribution is within 1,2,3 SD’s of the mean
68%
95.4%
99.7%
wha is a confidence interval
range of values which is likely to contain the mean of the population with some degree of certainty.
[𝑋̅ ± T × SEM]
T=t critical or t value
what p value denotes significance
less than 0.05
student t test
for comparing the means of two groups
-calculate the probability of obtaining the results or greater assuming there is no difference
-requires normal distribution of the population
paired t test
measure each subject twice
powerful (controlled)
