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NCS Prep > 17 Research and Statistics > Flashcards

17 Research and Statistics Flashcards

1
Q

Hierarchy of evidence

A 
1 Systematic reviewed and meta-analysis
2 RCTs
3 Cohort studies
4 Case-control studies
5 Cross-sectional surveys
6 Case reports
7 Expert opinion
8 Anecdotal
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2
Q

Nominal measurement

A

Labels, mutually exclusive, exhaustive

Male and female

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3
Q

Ordinal measurement

A

Rank ordering, distance between ratings not equal

1st, 2nd, 3rd place

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4
Q

Interval measurement

A

Equal intervals between ratings, no true zero

Temperature

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5
Q

Ratio measurement

A

Equal intervals, true zero

10-m walk time

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6
Q

Reliability

A

Consistency, dependability
Random and systemic errors limit reliability
Data must be reliable before considered valid

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7
Q

Standard error of measurement

A

How repeated measures on same instrument tend to be distributed around true score
Large SEM = low reliability

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8
Q

Construct validity

A

How well test measures the abstract construct it’s supposed to measure, like pain, intelligence, QOL

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9
Q

Content validity

A

How well content of test matches a content domain associated with the construct
Usually refers to surveys or questionnaires

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10
Q

Face validity

A

Under content validity

Test appears to test what it’s supposed to

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11
Q

Criterion-related validity

A

Compares test with other measures already validated (gold standard)
Concurrent- measured at same time as other
Predictive- compare to future measure

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12
Q

Floor effect

A

A measure’s lowest score is unable to assess a patient’s level of ability

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13
Q

Ceiling effect

A

A measure’s highest score is unable to assess a patient’s level of ability

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14
Q

Normative data

A

Represents scores pulled from literature to provide normal values for specific variables within a population
Provides approximate guidelines

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15
Q

Minimal detectable change

A

Minimum amount of change in a patient’s score that ensures the change is not the result of measurement error

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16
Q

Minimal clinically important difference

A

Smallest amount of change in an outcome that might be considered important by patient or clinician

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17
Q

Sensitivity

A

True positive rate
Likelihood that someone with condition will be positive on test
High = few false negatives

18
Q

Specificity

A

True negative rate
Likelihood that someone without condition will be negative on diagnostic test
Low = more false positives

19
Q

Positive predictive value

A

Percentage of people who are positive on the diagnostic test who have the condition

20
Q

Negative predictive value

A

Percentage of people who are negative on the diagnostic test who do not have the condition

21
Q

Positive likelihood ratio

A

Indicates how many times more or less likely a positive test result will occur in someone with condition than without
True positive compared to false positive rate
Large >10
Moderate 5-10
Small 2-5
Neutral 1

22
Q

Negative likelihood ratio

A 
Indicates how many times more or less likely a negative test result will occur in someone without condition than in someone with
True negative compared to false negative
Large <0.1
Moderate 0.1-0.2
Small 0.2-0.5
Neutral 1
23
Q

Measures of central tendency

A

Mean
Median
Mode

24
Q

Best measures of central tendency for data

A

Nominal = mode
Ordinal = median
Interval/ratio (not skewed) = mean
Interval/ratio (skewed) = median

25
Q

Percentiles/quartiles

A

25th percentile = Q1
50th = Q2
75th = Q3

26
Q

Standard deviation on normal distribution/bell curve

A
  1. 2% within 1 SD of mean
  2. 4% within 2
  3. 7% within 3
27
Q

Intraclass correlation coefficient

A

Measure of reliability of ratings
Describes how strongly units in the same group resemble each other
Ranges 0-1 (low to high agreement)
ICC >0.75 is good reliability
Low if poor agreement between raters or if there is not much variability between subjects

28
Q

Inferential statistics

A

Allow us to use samples to make generalizations about the populations the samples represent

29
Q

Null vs experimental hypothesis

A 
Null = No relationship between X and Y
Experimental = Relationship between X and Y
30
Q

p-values

A

Probability of observing your sample results given that the null hypothesis is true
p = 0.05 means 5% chance of finding a difference as large as or larger than the one in your study given that null is true
p<0.05 means reject null, X and Y are different

31
Q

Parametric stats

A

Interval or ratio scales
Assumes normal distribution
Assumes variance in data for the samples compared are roughly equal

32
Q

Nonparametric stats

A

Nominal or ordinal scales

Does not rely on assumptions about population

33
Q

Significance testing for 2 independent groups

A 
Parametric = unpaired t-test
Nonparametric = Mann-Whitney U test
34
Q

Significance testing for 2 related scores

A 
Parametric = paired t-test
Nonparametric = Wilcoxon signed-rank t-test
35
Q

Significance testing for 3 or more independent groups

A 
Parametric = One-way analysis of variance (ANOVA)
Nonparametric = Kruskal-Wallis analysis of variance by ranks
36
Q

Significance testing for 3 or more related scores

A 
Parametric = One-way repeated measures ANOVA
Nonparametric = Friedman two-way analysis of variance by ranks
37
Q

r-squared

A

Measures percentage of variation in the values of the dependent variable that can be explained by the variation in the independent variable
Ranges 0-1
r-squared = 0.84 means 84% of variance in Y can be explained by changes in X; remaining variance is random variability

38
Q

Confidence interval

A

Range of values likely to encompass the true value
Confidence level is probability that CI encompasses true value
Higher CL is wider CI

39
Q

Type 1 error

A

False positive

Fire alarm goes off without fire

40
Q

Type 2 error

A

False negative

Fire alarm does not sound with fire

41
Q

Statistical power

A

Probability of type 1 error is associated with level of significance (alpha)
Probability of type 2 error is beta
Power = 1-beta
Power means x% chance that treatment effect will be detected

42
Q

How to increase statistical power

A

Increasing alpha (p from 0.05 to 0.01)
Increasing sample size
Large effect size (can have smaller sample if expect large effects)

NCS Prep (19 decks)

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