Algebra & Biostatistics Flashcards
Accuracy
How close the average of measured values are to the true value.
- improved by making replicate measurements & taking the average
- assessed by calculating the percent error
Precision
How close measured values are to each other. “ Agreement b/w replicate measures”
- improved by careful lab technique &/or using instruments capable of yielding greater precision I.e. More significant figures
- standard deviation is a measure of precision
Peta
P
10^15
1E+15
Tera
T
10^12
1E+12
Giga
G
10^9
1E+09
Mega
M
10^6
1,000,000
Kilo
k
10^3
1,000
Hecto
h
10^2
100
Deca
da
10^1
10
Ten
Deci
d
10^-1
0.1
Tenth
Centi
c
10^-2
0.01
Hundredth
Milli
m
10^-3
0.001
Thousandth
Micro
u
10^-6
0.0000001
Millionth
Nano
n
10^-9
1E-09
Billionth
Inferential Statistics
Used to draw conclusions about the data
Trying to reach conclusions that extend beyond the immediate data alone
Are the two groups different?
Categorical Variables
- Nominal
- Ordinal
- Dichotomous
Continuous Variables
- Interval
- Ratio
Nominal Variables
- no intrinsic order
- example: color of shirts.
- No mean or median, but can have a mode.
Ordinal Variables
- Have order
- example: scale of 1-5 on how much you like tofu
- has a median and a mode, may have a mean
Dichotomous Variables
- only has 2 values
- example: male or female
Interval Variables
- numerical value & is measured.
- example: age, height, temperature, years of nursing
- has a mean, median and mode
Ratio Variables
- like interval, but value of 0 indicates there is nothing
- can’t go below zero
- example: age, years of nursing, height
- has a mean, median and mode
Clinical Trial
Experimental study in which the exposure status (assigned to active drug vs. placebo) is determined by the investigator
Randomized Controlled Trial
A special type of clinical trial in which assignment to an exposure is determined purely by chance
Cohort Study
Observational study in which subjects with an exposure of interest (i.e. Hypertension) and subject without the exposure are identified and then followed forward in time to determine outcomes
PRO- few selectional bias CON- takes a long time
Case-Control Study
Observational study that first identifies a group of subjects with a certain disease and a control group without the disease, and then looks to be back in time to find exposure to risk factors for the disease. This type of study is well-suited for rare diseases
PRO- results are quick CON- a lot more selectional bias
Cross-Sectional Study
Observational study that is done to examine presence or absence of a disease or presence or absence of an exposure at a particular time
PRO- large group, quick results CON- unclear if exposure preceded the outcome
Bias
Any systematic error in the design or conduct of a study that results in a mistaken estimate of an exposure’s effect on risk of disease
Selectional Bias
Bias introduced by the way in which participants are chosen for a study
Confounding
This occurs when an investigator falsely concludes that a particular exposure is casually related to a disease without adjusting for other factors that are known risk factors for the disease and are associated with the exposure
Sensitivity
The ability of the test to identify correctly those who have the disease. It is the number of subjects with a positive test who have disease divided by all subjects who have the disease.
A test with high sensitivity has few false negative results
Specificity
The ability of the test to identify correctly those who do not have the disease. It is the number of subjects who have a negative test and do not have the disease divided by the number of subjects who do not have the disease.
High specificity has few false positives.
High specificity low sensitivity
Low specificity high sensitivity
