STT. Exam 2 Flashcards

1
Q

conditional probability formula

A

=Pr(little |big)

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2
Q

false positive:

A

test states the condition is present, but it is actually absent

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3
Q

false negative:

A

test states the condition is absent, but it is actually present

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4
Q

sample space

A

“S”, set of all possible outcomes

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5
Q

law of large numbers

A

the larger the number of trials, the more stable the probability will become

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6
Q

independent trials

A

outcomes do not affect each other

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7
Q

event

A

subset of sample space, ex. A {2,4,6}

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8
Q

probability

A

count in event (ex. A)/ total in S

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9
Q

probability is between two numbers:

A

0 and 1

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10
Q

certain event

A

the probability of an event that must occur, is 1

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11
Q

not A:

A

event that A does not occur

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12
Q

A and B:

A

both A and B occur (what overlaps!)

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13
Q

A or B:

A

event that both occur (don’t count overlap twice)

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14
Q

disjoint/mutually exclusive A and B means that:

A

they have no overlap

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15
Q

disjoint/mutually exclusive A and B formula:

A

P(A or B)= P(A and B) or P(A) + P(B)

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16
Q

A and B formula when trials are independent:

A

P (A and B)= P(A) x P(B)

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17
Q

complement rule:

A

P(not A or A compliment)= 1- P(A)

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18
Q

If A and B are disjoint, then…

A

P(A and B) = 0

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19
Q

If Pr(A and B) do not equal 0, then…

A

A and B are not disjoint

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20
Q

or=

A

add

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21
Q

and=

A

multiply

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22
Q

if A and B are independent, then:

A

P(A and B) = P(A) x P(B)

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22
Q

marginal

A

looking at columns, going “down”

23
Q

conditional

A

looking at rows, going “across”

23
if A and B are dependent, then:
Pr(A and B) = Pr(A) x Pr(B|A) Pr(A and B) = Pr(B) x Pr(A|B)
24
X=
random variable
25
E(X)=
expected value, mu, population mean
26
population mean notation:
mu
27
population SD notation:
sigma
28
sample mean notation:
x bar
29
sample SD notation:
s (little s)
30
important property of density curve:
areas under the curve correspond to relative frequencies
31
SD rule:
68% is 1 SD away 95% is 2 SD away 99.7% is 3 SD away
32
z-score formula:
x-xbar/SD
33
chap. 6 z-score formula:
x-mu/sigma
34
68% of data:
mu + or - sigma
35
95% of data:
mu + or - 2sigma
36
99.7% of data:
mu + or - 3sigma
37
center:
mu
38
spread:
sigma
39
area under the density curve represents the:
probability
40
normal distribution/ 'N' formula:
= N(center, spread) =N(mu, sigma)
41
standard normal notation for mu:
0
42
standard normal notation for sigma:
1
43
x follows what notation:
general normal, x=N(mu, sigma)
44
z follows what notation:
standard normal, z= N(0,1)
45
lower tail:
to the left
46
upper tail:
to the right
47
what tail is used to find percentiles?
lower tail (to the left)
48
population proportion:
p
49
sample proportion:
p-hat
50
sigma of p-hat formula:
square root of p times 1 - p-hat, all over n
51
SD rules for p-hat:
68%= p + or - SD formula 95%= p + or - 2 times the SD formula 99.7%= p + or - 3 times the SD formula
52
z-score p-hat formula=
= p-hat - p/ SD formula
53
sampling distribution notation for p-hat=
= N(p, SD formula)