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Epidemiology > Intro to Biostatistics > Flashcards

Intro to Biostatistics Flashcards

1
Q

What are the 3 primary levels (groupings) for variables?

A
  • Nominal
  • Ordinal
  • Interval or Ratio
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2
Q

What are the 3 attributes of data measurement that determines the groups?

A
  • Order/Magnitude
  • Consistency of scale/ Equal distances
  • Rational absolute zero
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3
Q

Nominal

A
  • Dichotomous/Binary
  • Non-ranked
  • Named categories
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4
Q

Ordinal

A
  • Ordered
  • Rank-able categories
  • Non-equal distance
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5
Q

Interval/Ratio

A
  • Order and magnitude

- Equal distances

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6
Q

Which levels of measurement are known as discrete?

A
  • Nominal

- Ordinal

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7
Q

Which level is known as continuous?

A

Interval/Ratio

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8
Q

After data is collected, we can appropriately go ___________ in specificity/detail of data measurement (levels) but never _________!

A

Down,

Up

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9
Q

Mode

A

Most common

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10
Q

Median

A

Middle when numbers are in order

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11
Q

Mean

A

Average

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12
Q

Interquartile Range

A

Range of the middle, innermost 50%

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13
Q

What is most useful in ordinal data?

A
  • Mode

- Median

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14
Q

What is most useful in nominal data?

A
  • Mode
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15
Q

What is most useful in interval?

A
  • Mean

But all three can be used

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16
Q

Variance

A

The average of the squared differences in each individual measurement and the mean.

the mean - measurement divided by the number of groups.

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17
Q

Standard Deviation (SD)

A

Square root of variance value

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18
Q

What are stats tests that are useful for normally-distributed data called?

A

Parametric tests

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19
Q

Positively Skewed

A
  • When the mean is higher than the median

- Tail pointing to the right

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20
Q

Negatively skewed

A
  • Mean lower than the median

- Tail pointing to the left

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21
Q

Skewness

A

A measure of the asymmetry of a distribution

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22
Q

What is the skewness value of the perfectly-normal or symmetric distribution?

A

Zero

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23
Q

Kurtosis

A

A measure of the extent to which observations cluster around the mean

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24
Q

What is the kurtosis value for a normal distribution?

A

Zero

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25
Q

Wha does a positive kurtosis mean?

A

More cluster

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26
Q

What does a negative kurtosis mean?

A

Less cluster

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27
Q

What are the required assumption of Interval/Ratio data?

A
  1. Normally-distributed
  2. Equal variances
  3. Randomly-derived and independent
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28
Q

What is the purpose of Levene’s test?

A

To assess equal variance between groups

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29
Q

How is data that is not normally-distributed handled?

A
  1. Use a statistical test that does not require the data to be normally distributed
  2. Transform data to a standardized value (z-score or log transformation)
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30
Q

Null Hypothesis

A

Researcher perspective which states there will be no true difference between the groups being compared

31
Q

Type 1 Error

A
  • Alpha
  • rejecting null hypothesis when it is true and should be accepted
  • claiming difference when there is none
32
Q

Type 2 Error

A
  • Beta
  • Accepting the null hypothesis when it is actually false and you should not have accepted it
  • claiming there is no difference when there is one
33
Q

1 SD above and below the parameters will represent ___ % of all people in the study.

A

68%

34
Q

2 SD above and below the parameters will represent ___ % of all people in the study.

A

95%

35
Q

3 SD above and below the parameters will represent ___ % of all people in the study.

A

99.7%

36
Q

Power

A
  • 1 - beta
  • the statistical ability of a study to detect a true difference if one truly exists
  • 80% by default
37
Q

What percentages of type 2 error is acceptable?

A

20%

38
Q

Sample size and power

A

the larger the sample size, the greater the likelihood of detecting a difference if one truly exists

increase in power

39
Q

What percentages of type 1 error is acceptable?

A

5%

40
Q

If a p value is ______ than the pre-selected alpha, (0.05, 5%), then we say that it is statistically significant

A

lower

41
Q

Interpretations of a p value

A
  • the probability of making a type 1 error if the null hypothesisi is rejected
  • the probability of wrongly claiming a difference between groups when one doesn’t really exist
  • the probability of obtaining group differences as great or greater if the groups were actually the same
  • the probability of obtaining a test statistic as high/higher if the groups were actually the same/equal
42
Q

Confidence Intervals

A

the range in which you are a certain percent confidant that the real difference lies

43
Q

What are the 4 key questions to select the correct statistical test?

A
  • What data level is being recorded
  • What type of assessment is desired?
  • How many groups
  • Is the data independent or related
44
Q

What is the name for the correlation test for nominal data?

A

Contingency Coefficient

45
Q

What is the name for the correlation test for ordinal data?

A

Spearman Correlation

46
Q

What is the name for the correlation test for inteval data?

A

Pearson Correlation

47
Q

What key words should you look for in a survival test?

A
  • time to event

- event occurrence

48
Q

What is the name for the survival test for nominal data?

A

log-rank

49
Q

What is the name for the survival test for ordinal data?

A

Cox-proportional Hazards test

50
Q

What is the name for the survival test for interval data?

A

Kaplan-Meier test

51
Q

What are the key words for a regression test?

A
  • prediction
52
Q

What is the name for the regression test for nominal data?

A

Logistic Regression

53
Q

What is the name for the regression test for ordinal data?

A

Multinomial Logistic Regression

54
Q

What is the name for the regression test for interval data?

A

Linear Regression

55
Q

What is the nominal test for independent data with 2 and 3 or more groups?

A
  • Chi square

- Fisher’s exact for cells less than 5

56
Q

What is the post hoc test for nominal data

A

bonferonni test

57
Q

What is the nominal test for related data with 2 groups?

A

McNemar test

58
Q

What is the nominal test for related data with 3 or more groups?

A

Cochran

59
Q

What is the ordinal test for independent data with 2 groups?

A

Mann-Whitney test

60
Q

What is the ordinal test for independent data with 3 or more groups?

A

Krusal-Wallis test

61
Q

What is the ordinal test for related data with 2 groups?

A

Wilcoxin Signed Rank test

62
Q

What is the ordinal test for related data with 3 or more groups?

A

Freidman

63
Q

What are the post hoc tests for ordinal data with 3 or more groups?

A
  • Student-Newman-Keul test
  • Dunnett
  • Dunn
64
Q

What is the interval test for independent data with 2 groups?

A

Student t test

65
Q

What is the interval test for independent data with 3 or more groups?

A
  • ANOVA

- MANOVA ( 2 or more dependent variables)

66
Q

What is the interval test for independent data with 3 or more groups with confounders?

A
  • ANCOVA

- MANCOVA

67
Q

What is the interval test for related data with 2 groups?

A

Paired t test

68
Q

What is the interval test for related data with 3 or more groups?

A
  • RM ANOVA

- RM MANOVA

69
Q

What is the interval test for related data with 3 or more groups with confounders?

A
  • RM ANCOVA

- RM MANCOVA

70
Q

What are the post hoc tests for interval data with 3 or more groups?

A
  • Student-Newman-Keul test
  • Dunnett
  • Dunn
  • Tukey or Sceffe tests
  • Bonferroni
71
Q

Student-Newman-Keul test

A
  • compares all pairwise comparisons possible

- all groups must be equal in size

72
Q

Dunnett test

A
  • compares all pairwise comparisons against a single control
  • all groups must be equal in size
73
Q

Dunn test

A
  • compares all pairwise comparisons possible

- useful when all groups are not equal in size

74
Q

Kappa statistic

A

correlation test showing relationshio of agreement between evaluators

-

Epidemiology (12 decks)

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