Measurement, Data Processing, and Analysis

What is Qualitative data?

non numerical information obtained from observations

What is quantitative data?

numerical data obtained from measurements

Three types of error

Human, random, systematic

Uncertainty in analog instruments

half the smallest division

Uncertainty in digital instruments

the smallest scale division

What is propagation of random errors?

shows the impact of uncertainties on the final result

Absolute uncertainties in addition and subtraction

uncertainties are added together if units are the same

Absolute uncertainties in multiplication and division

must be expressed as percentage uncertainties, which can be added together and converted into absolute uncertainties again

What are experimental errors?

difference between the recorded value and the literature/scientifically accepted value

What are systematic errors?

all results are either too high or too low

What are random errors?

some results are too high and others too low; random

How to calculate % error

abs(theoretical-experimental)/theoretical *100

How to calculate % yield

experimental/theoretical *100

How to calculate % uncertainty?

uncertainty for instrument/result *100

How to convert percentage uncertainties to absolute uncertainties?

% uncertainty/100 *experimental result

How to find absolute uncertainties from data?

largest value-smallest value/2

How is systematic error caused?

result of poor experimental design or procedure, or faulty equipment

How many sig figs in addition and subtraction

as many as the no. with the least sig figs

How many sig figs in multiplication and division?

as many as the no. with the least sig figs

What is precision in data?

the degree of closeness of measurements from one another; the repeatability error

What is accuracy in data?

The degree of closeness of measurements from the target/reference value