Quiz 2 Flashcards
population
the entire set you are interested in
- number of people interested in
sample
a subset of the population that is measured to make inferences about the population
- number of people actually tested
central tendency
what does the typical value look like
- average (mean, median, mode)
what is mode? and what is the problem with it?
the most common value in the distribution
- the problem is that this number is too sensitive to precision data
- almost never matches average
- zeros and outliers do not effect mode
median
- the value that separates the distribution into an upper and lower half
- separates values by frequency
- depending on the shape of the distribution, this may not be very representative
mean
the average value in the sample
- the most widely used metric
- most sensitive to zeros, extreme values, and outliers
variability
the extent to which measurements within the sample are different from eachother
determine the average hospital stay after recovering from appendix removal
A=5 days. B= 4 days. C= 10 days. D=2 days.
E=8 days
5+4+10+2+8=29/5=5.8
calculate the sum of squares if 5.8 is your mean.
A= 5 days
B= 4 days
C= 10 days
D= 2 days
E= 8 days
5-5.8= (-0.8)^2=0.64
4-5.8= (-1.8)^2=3.24
10-5.8= (4.2)^2=17.64
2-5.8= (-3.8)^2= 14. 44
8-5.8= (2.2)^2= 4.84
0.64+ 3.24+17.64+14.44+4.84= 40.8
calculate variance if sum of squares is 40.8 and sample size is 5
S^2= (40.8)/(5-1)=10.2
calculate standard deviation if we know the variance is 10.2
square root of 10.2 =3.19
- so, s=3.19
how far above average is patient A’s diastolic blood pressure?
AVG= 80
STDEV= 15
Patient A= 98
(98-80)/15=1.2
uni modal
single common value
poly modal
has many common values
bi modal
- has two common values
bell curve
- symmetrical
- uni modal
- mode, median, and mean are the same
