Probability and Statistics Flashcards

1
Q

probability

A

the measure of how likely a particular event or outcome is to occur

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2
Q

statistics

A

the analysis and interpretation of numerical data

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3
Q

factorial n!

A
  • product of all positive integers from 1 to n
  • for example
    6 ! = 6 x5x4 x3 x2x1= 720
    -equal to the number of ways of arranging n distinct objects in a sequence
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4
Q

permutation

A
  • an order-conscious subset of elements taken from a set
  • order is significant –abc and bca are different permutations
    For example if a set contains a,b,c and d, 24 permutation of three elements are possible: abc, abd, acb, acd, adb, adc, bac, bad, bca, bcd, bda, bdc, cab, cad, cba, cbd, cda, cdb, dab, dac, dba, dbc, dca, dcb
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5
Q

combination

A
  • a subset of elements taken from a set
  • order is not significant– abc and bca are the same combination
    For example, if a set constains a,b,c and d four combinations of three elements are possible: abc, abd, acd, and bcd
    The combination abc could also be written as acb, bac, bca, cab, or cba. All six represent the same combination
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6
Q

set

A

a collection of elements

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7
Q

elements

A

a single item or outcome

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8
Q

outcome

A

a possible result of an experiment or trial

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9
Q

event

A

A set of outcomes that satisfy a particular condition

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10
Q

sample space, S

A
  • the set containing all possible items or outcomes in the situation being studied
  • also called universe, U
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11
Q

independent events

A
  • if the success or failure of event A has no affect on the probability of even B, then the two events are independent
    For example, a die is rolled twice:
  • Event A is rolling a six on the first roll of a die
  • Event B is rolling a six on the second roll
    Events A & B are independent
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12
Q

dependent events

A
  • If the success or failure of events A affects the probability of event B, then the two events are dependent
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13
Q

mode

A

the value that occurs most frequently in the sample set

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14
Q

median

A

the point in the sample set at which there are equal numbers of samples above and below

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15
Q

mean

A

the sum of all samples in the set divided by the numbers of samples

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16
Q

weighted arithmetic mean

A
  • used when some data are more significant than others

- wi= weight assigned to datum, Xi

17
Q

geometric mean of the sample

A
  • the number that, when raised to the power of the sample size, gives the product of all samples
18
Q

root mean square value

A

the square root of the arithmetic mean of the squares of all squares

19
Q

standard deviation

A

measures amount of dispersion in data set

  • low means that data tend to be gathered close to mean value
  • high means that data tend to be spread out over wide range of values
20
Q

variance

A

the square of the standard deviation

21
Q

random variable

A

assigns a real value to each possible sample point in sample space

22
Q

discrete random variables

A

there are finite numbers of possible numbers that the random variable can take on

23
Q

continuous random variables

A
  • the random variable can take on any value over an interval on the real number line
24
Q

probability density function (PDF)

A
  • Provides probability to each numerical output of the random variable (RV)
  • In the case of continuous RV, the PDF gives the density at that point
  • In the case of discrete RV, the PDF is a sum of impulses, each impulse with a magnitude of the probability equal to that numerical outcome
25
Q

binomial distribution

A
  • Given n trials the binomial distribution provides the likelihood that there will x successes
  • n is the number of trials
  • p is the probability of success
  • q is the probability of failure whre
    q=1-p
26
Q

normal or Gaussian distribution

A
  • frequently occurring a natural distribution when multiple random parameters all effect the outcome
27
Q

unit normal table

A
  • the probability density function, f(x) is difficult to evaluate
  • instead, it is common to use a unit normal table to find values for the corresponding cumulative distribution function Fx(x)
  • a unit normal table is normalized for a mean of zero and a standard deviation of one
28
Q

t-distribution

A

estimating statistics of normal distribution when sample size is small

  • arises when using sample mean and variance as estimates for normal distribution
  • student’s t-test used for testing significance of difference between two sample means
  • as number of degrees of freedom increases, t-distribution approaches normal distribution
29
Q

hypothesis testing

A

the process of making decision with a specified level of confidence about a statistical parameter being evaluated

30
Q

common hypothesis tests

A
  • Determine whether the average value taken from n samples could have come from a certain type of distribution
  • Determine whether the sample variance taken from n sample could have come from a certain type of distribution
31
Q

null hypothesis H0

A

assumption being tested

32
Q

alternative Hypothesis, H1

A

must be true if H0 is not true