W1 Errors and Confidence Interval Flashcards
what is systematic error
shows consistent error. all errors are of the same size, magnitude and direction
Eg: instrumental, method and human error
what is random error
errors that cannot be eliminated and can be treated statistically
how to find percentage relative uncertainty
absolute uncertainty/magnitude of measurement x 100%
how to round off for addition and subtraction of measurements
answer can contain no more DECIMAL PLACES than the least accurate measurement
how to round off for multiplication and division
answer can contain more SIGNIFICANT FIGURES than the least accurate measurement
how to report final % error in final answer
report final % error to nearest whole number
if less than 1%, report to 1dp
how to round off numbers
round up when digits after the desired digit >5
round down when digits after desired digit <5
round to nearest even digit when number is exactly halfway
what is the gaussian distribution
a graph that describes the distribution of results when an experiment is repeated several times and the errors are purely random
what is confidence interval for the mean
the range of values within which the population mean (or “true” mean) is expected to lie with a certain probability
how to do rounding off for mean and standard deviation
round to one more decimal place than original data if data set is more than or equals to 10
use the same number of decimal places as data sat if data set is less than 10
3 types of t test
comparing a measured result with a known value
comparison of the means of two methods one one sample measured multiple times
using two methods to make single measurements on several different samples
