Blog Entry for Forensic Tri-Lab Set One

1. What role do multiple observations/experiments play in making good inferences and conclusions in each case?
By looking at a lab in a variety of different ways, things add up better. For examlple, a soil sample with a similar PH as another but a completely diferent conductivity and water absorbancy may not be a match for the crime scene soil. Had you only tested the PH of the two soils, you may not know that it doesn't match up with the crime scene soil. When you observe things in many different ways, it allows you to get a better picture and gives you a more accurate answer/inference.


2. When is it hard to be precise and how does this affect the confidence in your results? What did you do about this?
When doing the Fiber lab, I sometimes got a large piece of string to burn, sometimes a small one, and the same inacuracy went for distances from the flame. There were many instances like this when it was pretty much impossible to be precise. In the firearms lab, it was hard for me to get exact measurements of the land and groove width and many other things as well. In the soil lab, you had to pick one of the two numbers for the PH that flashed on the screen and it was hard to make sure that no water went around the edges of the filter without passing through the soil when conducting the water absorbancy. It sometimes felt weird to have to approximate the results of an experiment, but I had to stop myself and realize that in the end, we were going to be making inferences anyway about who commited a crime and that it wasn't the end of the world if something was off by a very small amount. It did, however sometimes make me fell unsure when I chose which suspect was guilty since some tiny things went wrong and I couldn't be 100% sure.


3. When can you rely on "known" data to match up and when do you need to generate your own? What is the difference?
I don't fully understand this question.

Blog Entry for Blood Spatter Lab One

Question 1:

How did multiple drops at each height affect your results? What is the purpose of multiple trials in an experiment?

Answer:

Having multiple drops from each height made it so that if something went wrong with one drop, there were two other times to correct your mistakes. Also, if something went wrong that you were unaware of, having multiple drops is a great way to realize your mistakes. If you only drop the blood from each height once, it is extremely likely a drop will go wrong, throwing off the results.

Question 2:

What did you discover about the influence of height on blood diameter in a blood spatter?Could you now accurately infer the height at which a blood drop originated based on the diameter of a blood spatter?Why or why not?

Answer:

The higher the blood was dropped, the messier the spatter was (typically). Sometimes, there were multiple drops or splashes that occurred when blood was dropped from high heights. Other times, it ran down the side of the ruler. Still others, a bubble of air formed in the droplet, causing the drop to change. Only if no problems occur will you be able to make good inferences about the height the spatter was dropped.