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Epidemiology Exam 3 > Biostats > Flashcards

Biostats Flashcards

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1
Q

What are the three groupings for data variables?

A

Order/Magnitude

Consistency of scale/equal distances

Rational Absolute Zero

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2
Q

____ determines the appropriate statistical test

A

Data Type

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3
Q

What does order or magnitude mean?

A

Can you quantify the difference?

Is something bigger or smaller than something else?

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4
Q

What does consistency of scale or equal distances mean?

A

Does the value have units

Can you show the difference between values consistently

Can you calculate the range

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5
Q

If you see a dichotomous data set, automatically think its what type of data?

A

Nominal

Ex: Smoking/Non-Smoking
2 Age groups

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6
Q

Give an example where nominal data can have multiple categories

A

Car Brands: Ford, Dodge, Honda etc

Ice Cream Flavors: Chocolate, Strawberry, Cookies n’ Cream

In healthcare, a number association with a blood test or outcome is still nominal since there is no relationship of magnitude between the test and the number associated with it

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7
Q

What are the attributes for nominal data?

A

No order or magnitude (no quantitative association)

No consistency of scale or equal distances

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8
Q

Explain Ordinal data and include the two elements

A

Order, rankable data

There is order or magnitude but NO consistency of scale or equal distances. No way to quantitatively separate pain scale elements

Ex: Pain Scale, Income Brackets, SES

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9
Q

Explain Interval data (2) with include the two elements

A

Interval data can have negatives
Ratio has an absolute zero (physiological parameters)

Does have order/magnitude and does have consistency of scale

Ex: A1C, Height, LDL, Speed

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10
Q

____ and ____ data are discrete while ____ data is continious

A

Nominal and Ordinal

Interval/ratio

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11
Q

What are the two measures of central tendency to identify spread or dispersion?

A

Variance

SD

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12
Q

What type of test is used for normally-distributed data?

A

Parametric tests

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13
Q

Describe a positively skewed data distribution

A

Asymmetrically distribution with one tail longer, right sided.

Mean > Median

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14
Q

Describe a negatively skewed data distribution

A

Asymmetrically distribution with one tail longer, left sided.

Mean < Median

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15
Q

Outliers (do/dont) influence mode

A

don’t

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16
Q

Outliers (do/dont) influence mean and median

A

do

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17
Q

If you have skewed data, you must rule out what kind of statistical test?

A

Interval data

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18
Q

What are the values from 1 SD, 2SD and 3SD?

A

68%

95%

99.7%

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19
Q

Kurtosis

A

Measure of the extent to which observations cluster around the mean

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20
Q

Positive Kurtosis

A

Narrow, tight bell curve with more clustering of mean

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21
Q

Negative Kurtosis

A

Fat bell curve with less clustering of mean

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22
Q

What are the 4 ways to determine if a data set is normally distributed?

A

Levene’s Test
Skewiness
Draw and Analyze a graph
Analyze Mean and Median

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23
Q

What are ways to deal with non-normally distributed data

A

Convert it into a standardized value: Z-Score “log” transferred the data
Drop the stat test to a ordinal test (non-parametric test)

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24
Q

Skewiness

A

Measure of the asymmetry of a distribution

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25
What descriptive statistical elements are useful for nominal data? ordinal data? interval data?
Nominal: Mode Ordinal: Mode and Median Interval: Mode, Median and Mean
26
Type I Error
Also known as Alpha Rejecting the null hypothesis when it is true (should have accepted it)
27
Type II Error
Also known as Beta Accepting the null hypothesis when it is false (shouldn't have accepted it)
28
What is power?
The statistical ability of a study to detect a true difference, IF one truly exists between group-comparisons, and therefore the level of accuracy in correctly accepting/not accepting the null hypothesis.
29
Greater the Power, greater the ____ ____
Sample Size
30
What are the elements that determine a sample size?
Minimum difference between groups deemed significant Expected variation of measurement Alpha (type I) and Beta (type 2) error rates and confidence interval (usually ranges from 90% to 99%).
31
P-value is associated with what kind of error? Type I or Type II?
Type I
32
Levene's Test checks for? What is null hypothesis?
Equality of variance Null: There is no difference and are equal
33
If Levene's Test P-Value is less than .05 then
variance are not equal and do not use t-test
34
What is the benefit of using confidence intervals over p-value?
Can infer p-value after knowing the variance and spread of data from mean.
35
For a confidence interval to be statistically significant, the values MUST be
One one side of the ratio of 1. In other words, directional words must both be greater/greater above 1.0 or less than/less than below
36
What is the relationship between confidence interval and precision?
If you increase the confidence interval, the precision decreases.
37
What is the purpose of the correlation?
It provides a quantitative measure of the strength and direction of a relationship
38
What are the first two question we must ask for picking a statistical test?
What kind of data are you collecting? | What kind of comparison/assessment is desired?
39
What is the correlation test for nominal data?
Contingency coefficient
40
What is the correlation test for ordinal data?
Spearman Correlation
41
What is the correlation test for interval data?
Pearson Correlation
42
What are the key words for correlation?
"Correlate" "Compare"
43
What is the comparison or assessment type for "event or "Time-to-event"?
Survival Test
44
What is the nominal survival test?
Log-Rank Test
45
What is the ordinal survival test?
Cox-Proportional Hazard test
46
What is the interval survival test?
Kaplan-Meier test
47
Time with respect to a clock is only pertaining to which type of survival test?
Interval: Kaplan-Meier Test
48
What is the keyword for survival test?
"Changes over time" "every 2 months over 36 months"
49
What is the comparison or assessment for "outcome prediction or association"? It uses a prediction by utilizing multiple variables to predict an outcome
Regression
50
What data can we obtain from a regression test?
Odds Ratio
51
What is the nominal regression test called?
Logistic Regression
52
What is the ordinal regression test called?
Multinomial logistic regression
53
What is the interval regression test called?
Linear Regression
54
What is the most common type of comparison/assessment?
Frequencies, Counts and Proportions
55
What two additional questions need to be answered when dealing with frequencies, count and proportions?
How many groups? Is the data independent or related?
56
What type of test is best for frequencies, counts and proportions with 2 groups of independent data?
Pearson's Chi square test
57
What type of test is best for frequencies, counts and proportions with 3 or more groups of independent data?
Chi-square test of independence
58
If you have independent data with a expected cell count of less than 5 for frequencies, counts and proportions we should use?
Fischer's Exact Test
59
What are buzzwords for related or paired frequencies, counts and proportions tests?
"pre vs post" "baseline vs end" "before vs end."
60
For statistically significant findings in 3 or more comparisons, one must perform ____ to determine which groups are different. Specifically, ____ to avoid _____.
Post-hoc testing Bonferroni test of inequality Risk of increasing type I error
61
For 2 groups of paired/related frequencies, counts and proportions we would use?
McNemar
62
For 3 or more groups of paired/related frequencies, counts and proportions we would use?
Cochran

Epidemiology Exam 3 (2 decks)

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