BIO 330 Flashcards Preview

Biology > BIO 330 > Flashcards

Flashcards in BIO 330 Deck (379)
Loading flashcards...
91

experimental artifacts

bias resulting from experiment, unnatural conditions
problem w/ experimental studies
should try to mimic natural environment

92

minimum study design requirements

knowledge of initial/natural conditions via preliminary data to ID hypotheses and confounding variables
controls to reduce bias
replication to reduce sampling error

93

study design process

develop clear statement of research question
list possible outcomes
develop experimental plan
check for design problems

94

developing a clear statement of research question

ID question, Ho, Ha
choose factors, response variable
what is being testes? will the experiment actually test this?

95

list possible outcome of experiment

ID sample space
explain how each outcome supports/refutes Ho
consider external risk factors

96

develop experimental plan
based on step 1

outline different experimental designs
check literature for existing/accepted designs

97

develop experimental plan based on step 2

what kind of data will you have- aim for numerical
what type of statistical test will you use

98

minimize bias in experimental plan

control group
randomization
blinding

99

minimize sampling error in experimental plan

replication
balance
blocking

100

types of controls

positive
negative

101

positive control

treatment that should produce obvious, strong effect
ensuring experiment design doesn't block effect

102

negative control

subjects go through all same steps but do not receive treatment- no effect

103

maintaining power with controls

add controls w/o reducing sample size- too many controls samples using up resources will reduce power

104

placebo effect

improvement in condition from psychological effect

105

randomization

breaks correlation btw explanatory variable and confounding variables (averages effects of confounding variables)

106

blinding

conceals from subjects/researchers which treatment was received
prevent conscious/unconscious changes in behaviour
single blind or double blind

107

better chance of IDing treatment effect if

sample error/noise is minimized

108

replication =

smaller SE, tighter CI

109

spacial autocorrelation

each sample is correlated w/ sample area
not independent (unless testing differences in that population)

110

temporal autocorrelation

measurement at one pt in time is directly correlated w/ the one before/after it

111

balance =

small SE, narrow CI

112

blocking

accounts for extraneous variation by putting experimental units that are similar into 'blocks'
only concerned w/ differences within block- differences btw blocks don't matter
lowers noise

113

factorial design

most powerful study design
study multiple treatments and their interactions
equal replication of all combinations of treatment

114

checking for pseudoreplication

check degrees of freedom, very large- problem
overestimate = easier to reject Ho- pretending we have more power than we do

115

determining sample size, plan for

precision, power, data loss

116

determining sample size, wanting precision

want low CI
n ~ 8(sigma/uncertainty)^2
uncertainty is 1/2 CI

117

determining sample size, wanting power

detecting effect/difference
plan for probability of rejecting a false Ho
n~16(sigma/D)^2
D is min. effect size you want to detect
power is 0.8

118

ethics

avoid trivial experiment
collaborate to streamline efforts
substitute models for live animals when possible
keep encounters brief to reduce stress

119

most important in experimental study design

check common design problems
sample size (precision,power,data loss)
get a second opinion

120

most important in observational study design

keep track of confounding variables