Midterm 1 Flashcards
1
Q
What makes a fair comparison?
A
Randomized participants
2
Q
Observations
A
Group of people/what surveying
3
Q
Variables
A
What’s being measure
4
Q
Categorical
A
small number of values
5
Q
Binary
A
2 possible values (yes or no)
6
Q
Nominal
A
order of categories is irrelevant
7
Q
Ordinal
A
order of categories is meaningful
8
Q
Discrete
A
values equal to integers
9
Q
Continuous
A
values on a continuum
10
Q
Histogram
A
graphical display of the distribution of quantitative data
11
Q
In a stem and leaf plot, which digits are the stem and which are the leaf?
A
Stem is 1st digits and leaf is last digit
12
Q
Central tendency
A
the middle of the data
13
Q
Variation
A
how “spread out” the data is
14
Q
Mean
A
average of all values in dataset
15
Q
Median
A
middle value
16
Q
Mode
A
most common value
17
Q
mean > median
A
right (positively) skewed
18
Q
mean < median
A
left (negatively) skewed
19
Q
mean = median
A
symmetrical
20
Q
Range
A
smallest and largest values in data
21
Q
Interquartile Range (IQR)
A
25th and 75th percentile (1st and 3rd quartiles)
22
Q
Varience
A
average of (X-X bar)^2
23
Q
Standard deviation
A
square root of varience
24
Q
What is the box of a box and whisker plot?
A
25th to 75th percentile
25
Scatter plot
Illustrates the relationship between 2 quantitative measures
26
Correlation
a numerical descriptive of the strength of a linear association between 2 variables
27
r > 0
higher values of one variable correspond to higher values of the other
28
r < 0
higher values of one variable correspond to lower values of the other
29
r = +/-1
perfect linear association
30
r = 0
no linear association
31
Cumulative incidence
proportion of individuals newly acquiring the disease over a specific period of time
32
Risk factor
variable that may increase or decrease the chance (risk) of outcome
33
Relative risk
a measure of the strength of an association
34
RR < 1
treatment is associated with lower risk of outcome
35
RR > 1
treatment is associated with higher risk of outcome
36
RR = 0
no association of treatment with outcome
37
How do you calculate relative risk?
risk (treated) / risk (untreated)
38
Risk difference
how much of the disease can be attributed to a risk factor
39
How do we calculate risk difference?
risk (treated) - risk (untreated)
40
RD < 0
treatment associated with lower risk of outcome
41
RD > 0
treatment associated with higher risk of outcome
42
RD = 0
no association of treatment with outcome
43
What is the wording when reporting risk difference?
percentage point increase/decrease
44
What is the wording when reporting relative risk?
Percent increase/decrease
45
What constitutes stronger association when comparing risk difference?
A value farther away from 0
46
Incidence Rate (IR)
number of people who develop a condition (incident events) per person in the population over time
47
What are the units for incidence rate?
per person-years
48
Censored
when participants drop out or have not had the event by the end of follow-up
49
Cumulative Incidence
similar to incidence rate but for a specific length of time. can't calculate if there are drop outs
50
Incidence Rate Ratio (IRR)
IR (treated) / IR (untreated)
51
IRR < 1
treatment associated with lower rate of outcome (protection)
52
IRR > 1
treatment associated with higher rate of outcome (harmful)
53
IRR = 1
No association between treatment and outcome
54
Incidence Rate Difference (IRD)
IR (treated) - IR (untreated)
55
IRD < 0
treatment associated with lower rate of outcome (protection)
56
IRD > 0
treatment associated with higher rate of outcome (harmful)
57
IRD = 0
No association between treatment and outcome
58
Prevalence
the fraction of individuals with the disease at one specific point in time
59
PR < 1
exposure associated with lower prevalence
60
PR > 1
exposure associated with higher prevalence
61
PR = 1
no association between exposure and outcome
62
Prevalence Ratio
PR
63
Prevalence Difference
PD
64
PD < 0
exposure associated with lower prevalence
65
PD > 0
exposure associated with higher prevalence
66
PD = 0
no association between exposure and outcome
67
Population
collection of all individuals (units) that you wish to make inferences about
68
Parameter
numerical value that would be calculated using all units in the population
69
Sample
subset of "units"
70
Estimate/statistic
numerical value that is calculated using all units in the sample
71
Sampling unit
the individual items or elements of the population that are to be sampled (individual people, census tracts, houses)
72
Sampling Frame
a list of all units in the population (census tracts, class list, entire households)
73
Probability sampling
each unit in the population has a known, non-zero chance of being selected from the population to be included in the sample
74
Simple random sample
randomly selected individuals from the population such that each individual has the same change of being selected
75
Stratified random sample
divide population into subgroups and take simple random sample from each subgroup
76
Systematic random sample
randomly choose a starting unit; sample ___th unit after the starting unit
77
Cluster sample
sample clusters of individuals (households, clinics, schools) and use all individuals in the cluster
78
Multistage random sample
sample in stages (1st = school, 2nd = classroom, 3rd = student)
79
Convenience Sample
samples that aren't selected probabilistically
80
Generalizability
a measure of how useful the results of a study are for a broader group of people or situations
81
When is a sampling method bias?
if it produces results that systematically differ from the population
82
When is a sampling method unbias?
if over repeated sample, the average of the estimates from those sample can be expected to equal the parameter in population of interest
83
Selection bias
the sampling procedure systematically includes or excludes a portion of the population
84
Social desirability or response bias
subjects may not answer truthfully
85
Hawthorne effect
alteration of behavior by the subjects of a study due to their awareness of being observed
86
Low variability / high precision (bull's eye)
estimates tightly cluster around each other
87
Unbiased (bull's eye)
estimates cluster around the bull's eye
88
Margin of error (MOE)
measure of the precision of an estimate and gives a plausible range of values for the parameter
89
What provide a higher level of evidence, experimental or observational studies?
Experimental
90
Experimental Study
Exposure or treatment is controlled by the researcher
91
Replication
Same treatments are assigned to different sampling units to help assess variation in the responses
92
Randomization
ensure that uncontrolled factors do not bias the experimental results
93
Observational Study
exposure or treatment is not controlled by the researcher. Researchers collect data from an existing situation
94
Confounder
a variable that changes the estimate of the association between the main independent variable of interest (exposure) and the dependent variable (outcome) by 10% or more
95
Mediator
variable in the causal pathway that is associated with exposure and outcome
96
Case Reports
Describe characteristics of a few individual patients
97
Ecological Study
a study of risk-modifying factors and health or other outcomes based on populations defined either geographically or temporally
98
Cross-sectional Study
Samples populations and measures diseased/not diseased and exposed/not exposed at the same time
99
Case-control Study
Samples diseased and not diseased individuals separately and then measures exposed/not exposed
100
Odds Ratio
odds of exposed among those with disease/odds of exposure among those w/o disease
101
OR of exposure comparing diseased to not diseased =
OR of disease comparing exposed to unexposed
102
Relative risk and odds ratio will always estimate the same direction of association
OR < 1 if and only if RR < 1
OR > 1 if and only if RR > 1
OR = 1 if and only if RR = 1
103
Odds ration is always at least as extreme as the relative risk
If RR < 1, then OR 1, then OR >/= RR > 1
104
When the risk of disease is relatively low, the OR and RR are similar
RR = OR
105
Cohort Study
Enroll healthy participants and follow over time to see who develops disease
106
Randomized Clinical Trial
Study population ---> randomize ---> split into intervention and control ---> measure outcome
107
Meta-analysis
a way of combining results from multiple existing studies
108
Pre-clinical work
testing of a drug in-vitro and in animals to get a sense of toxicity, metabolism, PK, dosing
109
Phase 1 CT
drug given to usually healthy volunteers to determine safety and appropriate dosing levels. no controls
110
Phase 2 CT
further explore safety and get an initial idea of efficacy. control group usually used
111
Phase 3 CT
large, definitive RCT designed to show safety and efficacy. usually double blind, placebo controlled
