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Biobehavioral > Biostats- Melissa Wells > Flashcards

Biostats- Melissa Wells Flashcards

1
Q

What is the Belmont Report?

A

Belmont report = basic ethical principles underlying proposed regulations for research

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2
Q

What are the three principles underlying the Belmont Report?

A
  1. Respect for persons (informed consent)
  2. Beneficence (assessment of potential risks and benefits)
  3. Justice (selection of people to be in the research)
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3
Q

What can be determined from an observational study?

A

Associations or correlations

NO CAUSALITY

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4
Q

What is an observational study?

A

a type of study in which individuals are observed or certain outcomes are measured. No attempt is made to affect the outcome (no treatment is given)

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5
Q

What is a cross sectional study?

A
  • a type of observational study

- one point in time where independent and dependent variables are measured at the same time

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6
Q

What are the three types of longitudinal studies? and how are they different?

A
  1. Trend- measure changes in population over time (ex: a survey of a college freshman each year)
  2. Cohort- measures change and follows a particular population over time (not necessarily the SAME people though)- prospective (followed for longitudinal time period)
  3. Panel- measure changes in the SAME people over time
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7
Q

Qualitative study characteristics and some examples

A
  • High validity
  • analysis of less structured data (open ended response, etc)
  • Focus groups, qualitative personal interviews, visual methodology
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8
Q

Quantitative characteristics

A
  • High reliability

- Often coupled with generalizable sampling procedures

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9
Q

Mixed methods include…

A

both qualitative and quantitative aspects of study

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10
Q

Type of nomothetic causation

A
  1. Correlation/Association
  2. Temporal Order (A before B)
  3. Non-spuriousness (correlation, but not associated)
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11
Q

What are the three main parts of the “classical experiment”?

A
  1. Independent and dependent variable
  2. Pre-testing & Post-testing
  3. Control and experimental groups
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12
Q

What is investigated in phase I of clinical trials?

A
  1. Safety
  2. Side-effects
  3. Metabolism
    Note: usually done on healthy volunteer, check metabolism in actual person
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13
Q

What is investigated in phase II of clinical trials?

A
  1. Ideal dosing

Note: Need patients with condition

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14
Q

What is investigated in phase III of clinical trials?

A
  1. Experimental vs. control

“Hallmark of Clinical Trials”

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15
Q

What is investigated in phase IV of clinical trials?

A

Continued evaluation of FDA-approved therapy (Post-market study)

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16
Q

What is the Hawthorne effect?

A

When researcher behavior affects behavior

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17
Q

What is a double blind study?

A

research and respondents don’t know which treatment is the control or experimental

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18
Q

What is external invalidity?

A

Applicability to real world, the sample population isn’t really representative of the real world.

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19
Q

What is internal invalidity?

A

anything other than the stimulus that influences results (history, change in maturation, testing, instrumentation, etc)

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20
Q

What is a case-control study?

A
  • type of observational study
  • a comparison of people who have a condition and/or receive a treatment (cases) with another group of people who are not affected by the condition (control)
  • needs to be RETROSCPECTIVE
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21
Q

Four methods/types of non-probability sampling?

A
  1. Purposive
  2. Convenience
  3. Snowball
  4. Quota
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22
Q

What is a good way to avoid sampling bias??

A

Use a probability sample (a random sample)

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23
Q

What is the goal of probability sampling?

A

to a create a sample as REPRESENTATIVE of the population as possible

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24
Q

Element vs. population

A

element = individual members of population

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25
Q

Population

A

entire set of elements

26
Q

Sampling frame

A

list of all elements in a population

27
Q

Parameter vs. statistic?

A 
Parameter = summary of given variable in population
Statistic= summary of given variable in a sample
28
Q

What is a sampling distribution?

A

all possible random samples that could be selected

29
Q

What are the four types of random sampling?

A
  1. Simple random sample
  2. Systematic
  3. Stratified
  4. Multi-stage Cluster (or cluster sampling)
30
Q

Explain simple random sample?

A

need a list
assign a numer
select by a random number generator

31
Q

Explain systematic random sample

A 
determine sample size
divide population by sample number
(called sampling interval L)
list and number elements
RANDOMLY SELECT START POINT
the select every k-th element with-in groups
32
Q

Explain stratified random sample

A

random sample from sub populations
stratify your list
sample with-in those strata
(this increases sampling error potential)

33
Q

What is sampling error?

A

variation in values of your sample mean compared to the population mean

34
Q

What are two ways to reduce sampling error?

A
  1. increasing sample size

2. increasing homogeneity

35
Q

What are some characteristics of the normal curve?

A
  • theoretical distribution of scores
  • perfectly symmetrical
  • bell shaped
  • Unimodal
  • Tails extend infinitely in both directions
  • Mean/Median/Mode are equal in center of curve
36
Q

What area of the curve falls within 1 standard deviation of the mean?

A

68%

37
Q

What area of the curve falls within 2 standard deviations of the mean?

A

95%

38
Q

What area of the curve falls within 3 standard deviations of the mean?

A

98%

39
Q

What is the critical z-score of a 95% confidence level? (when alpha = .05)

A

1.96

40
Q

What is the critical z-score of a 90% confidence level? (when alpha =.10)

A

1.65

41
Q

What is the critical z-score of a 99% confidence level? (when alpha = .01)

A

2.58

42
Q

What is confidence interval and how do you find it?

A
  • range within “true” parameters should lie

- CI= mean +/- (z-score x SE)

43
Q

How do you find the standard error when given the standard deviation?

A

SE = SD/ (sq rt of sample size)

44
Q

What is the z-distribution?

A

a special case of normal distribution where idealized mean is 0 and s.d. is 1

45
Q

What is the confidence/significance level?

A

probability that our sample statistic will with with-in a given confidence interval

  • we set this ahead of time= alpha
  • when alpha is = .05 we are 95% sure that the statistic will fall within the given confidence interval
46
Q

What can influence confidence intervals?

A
  • Confidence level (alpha can be lowered or raised)
  • Sample size (more confidence with larger samples, so smaller interval)
  • Variation: more variation= more error (averages, high standard deviations)
47
Q

Define hypothesis

A

a prediction about the relationship between 2 variables that asserts that changes in the measure of an independent variable will correspond to the changes in the measure of the dependent variable

48
Q

Research hypothesis (H1)

A

predicts differences and relationships

49
Q

Null Hypothesis (H0)

A

predicts no relationship or no difference

-WE TEST THE NULL HYPOTHESIS

50
Q

What is a test statistic?

A

a measure of how different finding is from what is expected from the null hypothesis

51
Q

What is the z-distribution?

A
  • to use normal curve to answer questions, raw scores of distribution must be converted into z-scores
  • critical regions are areas under the curve that include unlikely sample outcomes if the null hypothesis is true
  • z-critical establishes critical regions (size of this region is reported by alpha)
52
Q

Do you reject H0 if the test statistics falls into the critical region?

A

YES!

53
Q

What happens if the test statistic does NOT fall into a critical region?

A

FAIL TO reject null hypothesis

54
Q

What does a p-value tell you?

A

The probability of obtaining this finding if the null is correct

55
Q

p > alpha

A

we do NOT reject the null hypothesis

56
Q

p < or = alpha

A

REJECT the null hypothesis

-P-value is STATISTICALLY SIGNIFICANT

57
Q

Pearson’s correlation coefficient

A

-1 to 1
slopes
(closer to -1 or 1 the stronger the correlation)

58
Q

Type 1 error

A
  • rejecting the null when the null is true
  • False positive
  • Saying the are different, when they really are not
59
Q

Type II error

A
  • failing to reject the null when the null is false
  • False negative
  • Saying the are the same, when really they are not
60
Q

What is confounding variable?

A

A third variable that truly accounts for the relationship of two other variables, A and B
(ice cream sales correlates with crime rates - but one doesn’t cause that other, there is a confounding variable - summer

-A and B relationship considered spurious (no relation)

Biobehavioral (23 decks)

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