stat 2
Terms
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- frequency distribution
- constructed by classifying indicidual obs into categories corresponsing to fixed numeric intervals and plotting the # of observations in each catgeory versus category descriptor
-
normal distribution
[median = mena] -
data desc by a bell shape (gaussian) curve w/ a max
population mean
best estimate of true value - accuracy
-
degree w/c measured value
agrees w/ true value - error (bias)
- difference between a measured value and true value
- median
-
midmost value of data distribution
less affected by "outliers" or skewed distribution - mode
- most frequently occuring value useful for non-normal
- population variance
- used to desc the variability or spread of obs in a data dist
- finite # of observations
-
samples variance (s2)
can be used to desc variability or spread of observations in data distribution - range
-
used to desc the variability in data set
largest-smallest - std deviation
-
most common encountered estimate of variability
equal to square root of variance -
precision
(reproducibility) -
degree w/c replicated measurements made in exactly the same way agree w/ each other
often expressed as relative std dev (rsd, %rsd) - % RSD
- (S/X) X 100
-
std deviation of mean
std error of the mean -
- estimate of variability or error in the mean obt fr n obs
-used to establish confidence intervals for desc the mean of a data set or when comparing the means of 2 data sets