Distributions

Question 1

Normal Probability Plot

Answer 1

Used to assess normality of a data set
1. Plot histogram/dotplot and look for clear deviations from normality
2. Plot normal probability plot (straight-ish line is normal)

Question 2

Normal Distribution

Answer 2

Bell shaped curve with one peak
Sx changes the height/width of curve

Question 3

Normal Dist Spread

Answer 3

Within 1 Sx: 68%
Within 2 Sx: 95%
Within 3 Sx: 99.7%

Question 4

normalpdf

Answer 4

what % of points at EXACT value

What proportion of ___ have exactly x?

Question 5

normalcdf

Answer 5

what % of points fall within a certain range

What proportion of ____ have between (lower bound) and (upper bound)?

Question 6

invNorm

Answer 6

Find x value of cumulative proportion

What value is at the (area) percentile?

or put probaibility as area, mean=0, st.dev=1 for z-score

Question 7

binomial distribution

Answer 7

B inary succes condition (Succeed/ Fail)
I ndependent
N umber=> fixed number of trials
S uccess => fixed probability of success

Question 8

binomcdf

Answer 8

probability of up to x successes out of n number of trials

Question 9

binompdf

Answer 9

probability of exaclty x successes

Question 10

geometric distribution

Answer 10

repeating indepent events with fixed success/failure condition and fixed probability UNTIL first success

Question 11

geometpdf

Answer 11

probability that it takes exactly x trials to get success

Question 12

geometcdf

Answer 12

probability that it takes less than x trials to get success

Question 13

sampling distribution shape

Answer 13

if n>30: normal
if population=normal: normal

else: mimics shape of population distribution