BIO 330 Flashcards Preview

Biology > BIO 330 > Flashcards

Flashcards in BIO 330 Deck (379)
Loading flashcards...
61

CV used for

relative measures- comparing data sets

62

sampling distribution

probability distribution of all values for an estimate that we might obtain when we sample a population, centred at true µ

63

values outside of CI

implausible

64

how many quadrats to use

till cumulative number of observations asymptotes

65

law of total probability

P[A] = Σ P[B].P[A I B]
for all B_i 's

66

null distribution

sampling distribution for test statistic, if repeated trials many time and graphed test statistics for H_o

67

Type I error

P[Reject Ho I Ho true] = alpha

68

reject null

P-vale < alpha

69

Type II error

P[do not reject Ho I Ho false]

70

Power

P[Reject Ho I Ho false]
increases with large n
decreases P[Type II E]

71

test statistic

used to evaluate whether data are reasonably expected under Ho

72

p-value

probability of getting data as extreme or more, given Ho is true

73

statistically significant

data differ from H_o
not necessarily important- depends on magnitude of difference and n

74

why not reduce alpha

would decrease P[Type I] but increase P[Type II]

75

continuous probability
P[Y = y] =

0

76

sampling without replacement

ex. drawing cards
(1/52).(1/51).(1/50)

77

Bayes Theorem

P[A I B] = ΣP[B I A].P[A] / P[B]

78

P-value > alpha

do not reject Ho
data are consistent with Ho

79

meaning of 'z' in standardization

how many sd's Y is from µ

80

standardization for sample mean, t =

Ybar - µ / (s / sq.rt. n)

81

CI on µ

Ybar ± SE.tcrit
SE of Ybar
t of alpha(1 or 2), degrees of freedom

82

1 sample t-test

compares sample mean from normal pop. to population µ proposed by Ho

83

why n-1 account for sampling error

last value is not free to vary if mean is a specified value

84

1 sample t-test assumptions

data are a random sample
variable is normally distributed in pop.

85

paired t-test assumptions

pairs are a random sample from pop.
paired differences are normally distributed in the pop.

86

how to tell whether to reject with t-test

if test statistic is further into tails than critical t then reject

87

2 sample design compares

treatment vs. control

88

2 sample t-test assumptions

both samples are random samples
variable is normally distributed in each group
standard deviation in two groups ± equal

89

degrees of freedom

1 sample t-test: n - 1
paired t-test: n - 1
2 sample t-test: n1 + n2 - 2

90

confounding variables

mask/distort causal relationships btw measured variables
problem w/ observational studies
impossible to differentiate 1 variable