week 5 analysis of data Flashcards
what is variance
how much the data is spread from the mean
does a spread out graph have a small or large standard deviation
higher sd
does a small and tall graph have a small or large standard deviation
low sd
if all values in a data set are the same, what is the standard deviation
0
`what do z scores measure
how many standard deviations they are away from the mean
what is included in box plot
- min
- 1st quartile
- median
- 3rd quartile
- max
if mean is greater than the median how is the data skewed
right skewed
if the mean is the same as the median how is the data skewed
symmetrical
if the mean is less than the median how is the data skewed
left skewed
what is discriptive analysis
describes the sample not the population
what are parameters
summary measures describing the a population
according to the empericcal rule what percent of the data lies within 1 sd of the mean
68%
according to the emperical rule what percentage of the data lies within 2 sds of the mean
95%
according to the emperical rule what percentage of the data lies within 3 sds of the mean
99.7%
what is chebyshevs rule
no matter how the data is distributed at least (1-1/k^2)x100% of the values fall within k standard deviatons of the mean
what can scatter plots allow us to see
visually represent the relationship between 2 numerical values
what does covarience measure
strength of relationship between two numerical values
if cov(x,y) > 0 what direction are x and y going in relation to eachother
in the same direction
if cov(x,y) < 0 what direction are x and y going in relation to eachother
in opposite directions
if cov(x,y) = 0 what direction are x and y going in relation to eachother
are independent
what is the coefficient of correlation
measures strength of relationships between two numerical values
if the correlation coefficient is close to 1 what does that tell us about the relationship between x and y
strong positive relationship
if the correlation coefficient is close to -1 what does that tell us about the relationship between x and y
strong negative relationship
if the correlation coefficient is close to 0 what does that tell us about the relationship between x and y
weak linear relationship
Is the mean effected by extreme outliers
yes
is the median effected by extreme outliers
no
can mode be used in categorical data
yes
what is the geometric mean
rate of change in a variable over time
what is the geometric mean rate of return
measures the status of an investment overtime
what does skewness measure
Skewness measures the extent to which the data values are not symmetrical around the mean.
