Interfering and Modifying Inputs, Compensation, & Biostatistics

Question 1

Desired Inputs

Answer 1

measurands that the instrument is designed to isolate

Question 2

Interfering Inputs

Answer 2

quantities that inadvertently affect the instrument as a consequence of the principles used to acquire and process the desired inputs

Question 3

Modifying Inputs

Answer 3

undesired quantities that indirectly affect the output by altering the performance of the instrument itself

Question 4

How do we compensate for undesired inputs?

Answer 4

Inherent insensitivity & Negative Feedback loops

Question 5

Inherent Insensitivity

Answer 5

all instruments and components that are inherently sensitive only to desired inputs

Question 6

Negative Feedback Loop

Answer 6

a strategy to make the output gain less dependent on the transfer function

How it works: Takes a portion of the output at any instant of time and feeds it back to the input

Question 7

Benefits of a negative feedback system?

Answer 7

• stabilizes amplifier gain
• reduces nonlinear distortion
  *increases circuit stability
• increases input impedance/resistance
• decreases output impedance/resistance
  *reduces noise
  *improves frequency response and bandwidth
• more linear operations

Question 8

What are two types of compensation?

Answer 8

Signal Filtering & Opposing Outputs

Question 9

Signal Filtering

Answer 9

a device or program that separates data, signals, or material in accordance with specified criteria

Question 10

Input Filters

Answer 10

mostly uses mechanical, pneumatic, thermal, or electromagnetic principles to block out undesired environmental inputs

Question 11

Intermediate Filters

Answer 11

often modify the signal to be a more desirable frequency or match a template (signal or time dependent)

Question 12

Opposing Inputs

Answer 12

• Adds additional interfering inputs to cancel undesired output components
• requires quantitative knowledge or interfering input as well as how the inputs affect the output
• super cumbersome, better for static inputs (pressure, temp)

Question 13

Case-Series

Answer 13

describes the characteristics of a group

Question 14

Case-Control

Answer 14

uses individuals selected because they have or don’t have some outcome or disease and then look back to find possible causes or risks

Question 15

Cross-Sectional

Answer 15

analyze characteristics of patients at one particular time to determine the status of a disease or condition

Question 16

Cohort

Answer 16

prospectively ask whether a particular characteristic is a precursor or risk factor for an outcome or disease

Question 17

Mean

Answer 17

the sum of observed values divided by the number of observations

best for evenly distributed data

Question 18

Median

Answer 18

value for which half of the observations are smaller and half are larger

best for skewed data

Question 19

Geometric mean

Answer 19

the nth root of the product of observations

Question 20

Standard Deviation

Answer 20

measure of the spread of the data about the mean

Question 21

Coefficient Variation

Answer 21

standardizes the variation, making it possible to compare two numerical distributions measured on different scales

Question 22

Correlation Coefficient

Answer 22

a measure of the relationship between numerical values

positive coeff: variables move in the same direction
0 coeff: no correlation
negative coeff: variables move in opposite directions

Question 23

Sensitivity

Answer 23

the probability of its yielding true positive results in patients who actually have the disease

True positive/ (True positive + False Negative)

Question 24

Specificity

Answer 24

the probability of it yielding negative results in patients who do not have the disease

True negative/(True negative + False positive)