What are dependent and independent variables?
In experiments, independent variables are the variables that get manipulated and changed. It is the subject that is being tested. Dependent variables are the responses that are measured. They are outcomes that are dependent on the different independent variables provided. For example, pretend you are conducting an experiment on the amount of sunlight to give a plant. The independent variable is the amount of sunlight you provide to a plant, this is what is being changed. The dependent variable is the height of the plant growth. This outcome is due to the different independent variables provided.
What is a hypothesis?
A hypothesis is an educated guess or proposed explanation. Hypotheses are based off of observations and research. Hypotheses should be tested with experiments and their results will either support the hypothesis or reject it.
For example, if you notice that plants do not grow in darkness, you could make a hypothesis that states plants need sunlight to grow. Then you would run an experiment where you compare a few plants grown in the sun versus a few plants grown in complete darkness. If the results come back showing that the plants in darkness grew, and then the hypothesis would have to be rejected. If the results come back showing that the plants in darkness did not grow but the ones in sunlight did, then the results would help support the hypothesis.
What is the scientific method?
The scientific method is the process of conducting experiments that help answer questions about the world. The first part of the scientific method is to ask a question. Based on your observations, you might be curious on a particular matter and ask why does this happen? Or is this the cause of that? The second part of the scientific method is to do background research. Researching will help in gaining knowledge of the subject. It will also help with thinking up a hypothesis and in planning the experiment. The third step is to construct a hypothesis. Using the prior research and your own observations, an educated guess can be made. The fourth step is the experiment. To test your hypothesis, conduct an experiment that will prove if the hypothesis is true or false. If there is only one variable you are testing in your hypothesis like the amount of sunlight given to a plant, then there should only be one independent variable that is changed. If there is more than one variable, like the amount of sunlight as well as the amount of water given to a plant, there can be no direct causation of the amount of sunlight to plant growth since there are two factors in play. It is crucial that you must keep everything besides the independent variable consistent. The fifth step is to analyze the results to draw a conclusion, and the sixth step is to report the results. Did the results support the hypothesis or did it prove the hypothesis false? In either case, you became more knowledgeable on the subject due to the experimentation. If the hypothesis was false, you could always construct a new different hypothesis and try again!
What is food poisoning?
Food poisoning is when food is eaten which contains poisonous bacteria or toxins. Raw foods, unwashed fruits and vegetables, and food from animals are the most likely to carry the bacteria that can make people sick. After eating food that has been contaminated with bacteria such as salmonella or E. coli, people can develop symptoms such as upset stomach or nausea, stomach cramps, diarrhea, or fever.
What is a relative risk of infection (R.I.)?
The relative risk of infection is a ratio of the risk of infection of an exposed person to the risk of infection of a non-exposed person. The risk of infection is food poisoning in this case, so if the R.I. is around 1, then the food is not the cause of the food poisoning. If the R.I. is less than 0.5, there is a strong association that exposure to the food will actually prevent people from being infected. But if the R.I. is greater than 2.0, there is a strong association that exposure to the food will lead to food poisoning.
Oh no! An outbreak of food poisoning has occurred in your city! Sick residents want to know which restaurant is responsible for making them sick, and healthy residents need to know which restaurant to avoid. Your challenge is to make a hypothesis about which restaurant is responsible for the outbreak, and then collect data from people in the city about where they have eaten recently and whether they are sick. You will then use the data you’ve gathered to determine if your hypothesis is correct. The restaurants are losing business fast, so you need to act quickly to find out which one is the culprit. Grab your barf bag and get going!
