What are common sources of error in an experiment?

How and why goosebumps happens? Compare morphological and biochemical evidence supporting evolution? Does salt water conduct electricity? What does the prefix glyco mean? HNO is a acid? What are the do's and don't's in safety precautions to be followed in the laboratory? What is it called when you remove salt from water by heating the water until it vaporizes and leaves the salt behind? Why serendipity are important? Is a widely accepted explanation based on experimental results? If volts is 415 watts is 40000 how many amp need? What evidence helps to exclude overharvesting as the cause of the overall decline A)a similar decline in edible North American mushrooms B)absence of mushrooms near coal-burning powerplants in Indon? What are the advantages or disadvantages of using a washing machine? When did tower hill last erupt? What is scientific observation? What were some of the major inventions of the 1940s? How do you use thermostat in a sentence? What is a ucalalie? Do darker colored ice cubes melt faster than lighter colored ice cubes? Is For a hypothesis to have value it must be testable true or false? Is a dimension a parallel world?

What are common sources of error in an experiment?