Statistics Flashcards
What is random uncertainty?
-Scatter of measurements about a best value
-Result of poor resolution, noise of equipment, fatigue
What is systematic uncertainty?
-Poor calibration or methodology mistake e.g. errors in equipment change depending on temp
What are factors affecting error?
-Precision: Tendency to have values close together
-Accuracy: Tendency to mimic ‘‘true value’’
-Reproducibility: is ‘repeatability’
What is absolute uncertainty?
-Actual magnitude of uncertainty
-Approximate value
How do you calculate absolute uncertainty?
Δx ≈ xmax - xmin / n
What is relative uncertainty?
Fraction or percentage of the measured value
How can you remove uncertainty/error?
-Repeat measurements to form series
-Plot values on a scatter plot to show outliers
How do you calculate relative uncertainty?
Δx/x or Δx/x x100
What is normal statistical distribution?
-Parametric data
-Most continuous biological data
-Normally distributed
What is binominal statistical distribution?
-Non-parametric data
-Data in proportions or counts
-Only states e.g. alive and dead
What is poisson statistical distribution?
-Data is in counts
-Rare events or very large samples
How do you calculate frequency density?
Frequency density = frequency/width of frequency interval
How do you calculate probability?
Probability = no. of selected outcomes / Total no. of possible outcomes
