STA 2023_ Lecture 3 Summary Statistics

STA 2023: Lecture 3 Summary Statistics
objectives of summary statistics - correct answer--measuring center: mean and median
-measuring spread: Quartiles
-measuring spread: standard deviation
-choosing measures of center and spread

mean (arithmetic average) - correct answer-the most common measure of center
-to find, add the values and divide by the number of observations
-cannot resist the influence of extreme observations
(add values and divide by the number of observations)

median - correct answer-the midpoint of a distribution, the number such that half of the
observations are smaller and the other half are larger
- to find; arrange all observations from smallest to largest if n is odd then the media is the
center of the ordered list if the n is even the median is the average of the 2 center
observations in the ordered list

mean vs. median - correct answer--if the distribution is exactly symmetric, the mean and
median are exactly the same
-in a skewed distribution, the mean is usually farther out in the long tail than is the median

When qualitative, the first thing you do is - correct answer-graph! (histograms and stemplots)

what are the 2 teams? - correct answer-1) mean and distribution
2) median and IQR

mean symbol sample - correct answer-

mean symbol population - correct answer-

median symbols - correct answer-population: M
sample: m

size symbols - correct answer-population: N
sample: n

standard deviation symbol population - correct answer-

standard deviation symbol sample - correct answer-s

variance symbol population - correct answer-

variance symbol sample - correct answer-

the mean will always - correct answer-be closer to the tail than the median