1. What role do multiple observations/experiments play in making good inferences and conclusions in each case?
When you have more information it is easier to make more precise inferences. In the fiber lab we looked through the microscope at three different levels of magnification so we could compare each of them three times and get a better idea of which ones are similar to each other and more likely to be the ones from the killer and what ones cannot be the killer. After that to be sure you chose the rite fiber you burned them and compared the way they burn. In order to find the killer you have to take both tests and whichever fiber matched the fiber on the victim best with both tests is the fiber from the killer.
2. Why is it hard to be precise and how does this affect the confidence in your results? What did you do about it?
It is hard to be precise because it is impossible to be completely still or exact. You could bump the slate under the microscope, not be able to watch the fiber close enough when it burns, not be on the exact right point when you measure the bullets, or accidentally touch the ph measure to the dirt at the bottom. This can affect your confidence in your data by showing that it can't always be perfect and that sometimes you have to rely on your best inference. To fix these problems you can take a second measurement and decide which is more accurate.
3. When can you rely on "known" data to match up with and when do you need to generate your own? what is the difference?
You can rely on known data when you don't have the time or materials to gather the data yourself. Like in the blood spatter lab we had to rely on the known theory of gravity and that it would carry the blood drops to the paper. In our fiber lab we had to rely on the fact that each fabric was the one it was labeled as but we gathered what it looked like under a microscope and when it burned. You should generate your own data whenever you have the ability to. In the dirt lab you have to gather how much ph is in the dirt sample, how much water each sample holds, and how much conductivity is in each sample. One of the things you need to rely on is that the measuring instruments work the way they are supposed to.