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CLT > Lecture Exam 2 > Flashcards

Lecture Exam 2 Flashcards

92

1
Q

Sensitivity

A

Testing for true positives

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2
Q

Specificity

A

Testing for true negatives

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3
Q

T test graph

A

A graph that shows how data from each group differ in averages and using that to understand the results of the t test

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4
Q

F test

A

used to compare the variances of two or more groups or samples

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5
Q

X axis

A

represents the variable being measured or studied.

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6
Q

y axis

A

represents the frequency or density of observations for each value or category on the x-axis

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7
Q

Group Means

A

The mean of each group is represented by a line or a bar on the graph

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8
Q

Error bars

A

represent standard errors, standard deviations, or confidence intervals.

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9
Q

T value

A

This value quantifies the difference between the means of the two groups relative to the variability within the groups

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10
Q

Critical value or significance level

A

This value quantifies the difference between the means of the two groups relative to the variability within the groups

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11
Q

Distribution curves in t test

A

The curves with more degrees of freedom are taller and have thinner tails

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12
Q

F value

A

This value quantifies the variability between group means relative to the variability within groups.

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13
Q

Guissan Distribution

A

When the mean, median, and mode are all the same values to make a normal distribution

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14
Q

Precision

A

occurs when a consistent answer comes from repeated tests; consider a target with shots scattered all around, but the average position of all shots is near the bullseye.

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15
Q

Accuracy

A

Imagine a target with all shots clustered tightly but far from the bullseye. This scenario represents high accuracy

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16
Q

Reliability

A

A result that has both accuracy and precision

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17
Q

Variance

A

The precision of a group of numbers - How precise?

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18
Q

Variance formula

A

Each individual data point in the sample is subtracted by the mean and then squared. Add all values together and divide it by n - 1

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19
Q

Standard Deviation

A

Most frequent used measure of precision and is found by square rooting the variance

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20
Q

Standard Deviation Ranges

A

+-1SD range: Includes 68% of the data points, extending one standard deviation above and below the mean.
+-2SD range: This would include about 95% of the data points, extending two standard deviations above and below the mean.
+-3SD range: This would cover about 99.7% of the data points, extending three standard deviations above and below the mean.

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21
Q

Coefficient of Variation formula

A

s/mean x 100% = C.V

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22
Q

Coefficient of Variation

A

Used to compare to sets, and the lower the % of variable distribution the more precise

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23
Q

Quality assurance

A

A program/process that assures accurate results, monitors methods and instruments and proposes troubleshooting methods

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24
Q

3 activities of quality assurance

A

pre-analytical (wrong patient info), analytical (off measured) , post-analytical (misinformed reporting)

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25
Q

Quality control Material

A

material that is of the same matrix of patient sample and analyzed with sample ( use at least 2 different “levels” like normal and abnormal)

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26
Q

Quality control

A

Actual tests that give numerical statistical measures of error

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27
Q

Quality control analysis

A

Using a Levey-Jennings chart to record QC results and determine if method is control or not using Westgards multirules

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28
Q

What kind of errors can be predicted by a bell curve chart?

A

Random errors

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29
Q

Patient Test Management

A

Monitor sample from start to finish

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30
Q

CLIA ‘88

A

Mandates 2 levels of every assay type, and is run once per day or once per shift; the results are analyzed on LJ chart

31
Q

What does a shift look like on a LJ chart?

A

When all QC values are all distributed on one side of the mean for 5-7 consecutive days

32
Q

What kind of errors are shifts and trends caused by?

A

Systematic errors

33
Q

Lyophilized

A

freeze dried and reconsituted with water

34
Q

Prediluted

A

ready to use

35
Q

Ethylene-glycol based

A

liquid at 0 degrees Celsius

36
Q

What does a trend look like on a LJ chart?

A

Occurs when QC results either decrease or increase consistently over 5-7 days

37
Q

Westgard Multirules definition

A

set of quality control rules to interpret quality control results in the clinical laboratory

38
Q

Westgard Multirules

A

1_2s, 1_3s, 2 of 3_2s, R_4s, 4_1s, 9/10x

39
Q

Random error vs systematic error

A

Random error is from lack of precision and systematic error relates to lack of accuracy

40
Q

Which Westgard rule is usually violated because of a random error?

A

R4s

41
Q

How to get good test results?

A

Calibration using primary (reference materials) and secondary standards (calibrated from primary)

42
Q

“Reference” methods

A

these are the gold standards for extremely accurate and reliable

43
Q

Sensitivity formula

A

TP/TP+FN x 100

44
Q

Specificity formula

A

TN/TN+FP x 100

45
Q

Which federal law mandates specificity and sensitivity tests?

A

FDA, CLIA, CMS

46
Q

FDA

A

Food and Drug Administration

47
Q

CLIA

A

Clinical Laboratory Improvement Amendments

48
Q

CMS

A

Center for Medicare and Medicaid Services

49
Q

Examples of reference methods

A

microhematocrit, single channel cell counter, spectrophotometer

50
Q

“Definitive” methods

A

using sophisticated instruments that measure a specific substance of interest in its pure form

51
Q

A calibrator has _____ values

A

assigned

52
Q

Control Runs

A

used with QC material that has the same matrix as bio sample

53
Q

Commercial Controls

A

Not used as calibrators but used to monitor all procedures using 2 to 3 levels (normal, low abnormal, high abnormal) with assayed values and SD ranges

54
Q

Assayed values

A

the established values of a particular substance

55
Q

Efficiency

A

TP + TN / (TP + FP + TN + FN) x 100

56
Q

Predictive value

A

Positive Predictive value: TP/TP+FP x 100
Negative Predictive value: TN/TN+FN x 100

57
Q

Name 3 QC Materials

A

Lyophilized plasma, whole blood QC materials, body fluid control

58
Q

Null Hypothesis (H0)

A

no statistical significant difference between glucose results from both analyzers

59
Q

P= 0.05

A

Is the probability that the null h. is rejected when it is true

60
Q

Alternate hypothesis (Ha)

A

statistically significant difference between glucose results from both analyzers

61
Q

Two-tailed test

A

examine whether there is a difference between groups or conditions in any direction by using H0 and Ha (H1)

62
Q

Paired T test

A

compares related measurements to assess whether there is a difference between paired data points

63
Q

Unpaired T test

A

There is no direct link or matching between data points in one group and data points in the other group; can be 1 tailed or 2 tailed

64
Q

Linear Regression Analysis by the method of Least Squares

A

Results from two tested methods plotted on linear graph where the results from the reference method (x axis) and the test method (y axis); if both tests are identical, there is a perfect correlation(r) and a linear line

65
Q

Linear Regression formula

A

yc = mx +b

yc = predicted y intercept derived

66
Q

Precision study

A

mandated by the CLIA to be a part of the method validation process and can be determined by SD and C.V

67
Q

F test

A

used when there are more than 2 means to compare

68
Q

Spearman, Kendall, and Pearson

A

names associated with different methods of measuring the strength and direction of relationships between variables

69
Q

Pearson correlation coefficient

A

often denoted as r, measures the linear relationship between two continuous variables. It ranges from -1 to +1, where:

  • r=+1 indicates a perfect positive linear relationship,
  • r=−1 indicates a perfect negative linear relationship,
  • r=0 indicates no linear relationship.
70
Q

Spearman’s (ρ (rho)) rank correlation coefficient and Kendall’s (tau (τ)) correlation coefficient

A

measures the strength and direction of the monotonic relationship between two variables (spearman is more commonly used)

71
Q

Monotonic

A

refers to a specific pattern or direction of change in a relationship between variables

72
Q

Critical values

A

z values in rejection area of a tail test

73
Q

how to find z score based on confidence level?

A

1-critical value (confidence level divided by 100) / 2 and then look for number on z-score table, add it up and theres the z score

74
Q

Formula for Least Squares method

A

y = mx + b

m = n (summation of x values) - summation of xy / n (summation of x^2) - (summation of x)^2

b = summation of y - m (summation of x) / n

CLT (6 decks)

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