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lec#10&11 Stats and Hypothesis testing
Terms in this set (23)
How are stats used in the lab?
-ranges for QC
What is the difference between a population and a sample?
A sample is a subset of a population
pop: all adult males
sample: all adult males born between 1990-1999
what is a parameter used for?
set limits on what you want to study
what are the three measure of central tendency?
what are the measures of dispersion?
True or false: Measures of central tendency indicate the degree of accuracy for the data under investigation
what do the measures of dispersion measure?( hint: there are 3)
-variation(low variation=high precision
-spread of data
How do we calculate range from..
1)a mean value(within 95%)
1)finding and using st. dev
2) subtracting the lowest value from the highest
what does variance indicate? and how is it calculated?
=[sum(result-mean)^2]degrees of freedom:aka number of results-1
what is the calculation for the coefficient of variation and what does this value allow us to do?
used to two or more groups of data
how do you calculate the standard error of the mean and what does this measure?
how well the sample mean estimates the population mean
True or false: The F test examines whether the means of two groups are statistically different that each other
false; that is what the Test does the F test estimates precision of a new method.
In a linear regression the ______ is plotted on the x-axis, and the __________ is plotted on the y axis.
a) concentrations, test method
b) test method, reference method
c)reference method, test method
d) test method, concentrations
C) reference method on the x-axis, and the test method on the y-axis
True or False: A Gaussian distribution only occurs when the mean=mode=median
True or false: Linear regression measures accuracy and precision
False; linear regression compares two different procedures and allows us to see if values are related
which is not a sample requirement:
a) 30 testing events
b)clinical decision points
d)testing identical samples
e) all are sample requirements
c) null hypothesis
what is the difference between a one tailed and two tailed test?
a two tailed test is non-directional
-the mean is/is not______
one tailed test is directional
-the mean is larger/smaller than_________
what does alpha represent?
alpha is the level of significance and is the probability of incorrectly rejecting the null hyp
p>a- weak evidence ---> fail to reject
p<a- strong evidence----> reject
what is the calculation for the F test and what is it comparing?
F=larger varience/smaller varience
if the number of data points used is large, this allows for______ variation.
if the F value calculated is less than the value on the F chart we _____ the null hypothesis.
A)fail to reject
A)fail to reject/no statistical difference
The T test compares..
e)none of the above
what is the calculation for the t-test? and when should you not perform a t-test?
[the mean of the differences*sqrt #of samples]/standard dev of differences
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