A good Experiment (Part 3)

Hypothesis

A Hypothesis is the first part of any experiment. It is a proposed explanation made on the basis of limited evidence. This serves as a starting point for further investigation. The primary criteria for a hypothesis is ability to be tested and the guess is made because of knowledge that has already been gathered. This is the point where the experiment starts as it/s purpose is to test the hypothesis.

Independent Variable

When an experiment takes place, you want to test a certain circumstance and to test what is actually going causing a phenomena. In order to figure out what is going on we like to limit the variables that change. The independent variable shows no dependence on other variables and is controlled by the scientist. This is the variable that causes change in the dependant variable. For example turning on the tap causes the water pressure out of the tap to increase.

Dependant Variable

This variable is affected by the independent variable. It is also the variable that is measured and studied during the experiment. If for example in an experiment they were looking at growth over time, the time allotted would be the independent variable and the amount of growth would be the dependant variable. It is named as such because of its dependence on the independent variable.

Control vs. Experimental groups

The control group in an experiment is not changed and is used as a ‘in a normal circumstance’. It is the base line that the scientists test against. The experimental group changes one of the variables are changed to test the hypothesis. The purpose of the control group along with the experimental group is to reduce to amount of variables that could be contributing to a change so testing it become easier. For example to plants are grown in the same soil and treated the same. One of them is given fertilizer. This gives the runners of the experiment a base line and they can see how much the fertilizer works.

Constants

In an experiment, constants are any variable that cannot or is not changed. He reason for constants is to keep the majority of possible variable unchanging so you can figure out what is going on more definitively. An example of this would be like in the previous example, the plants are in the same soil, taken care of the same way, etc.

Ways to improve Validity and reliability

Taking all the other steps are a good start to conducting a good experiment but the validity and being able to repeat it are very important aspects as they help prove the point you are trying to make. There are many different strategies to conducting a more reliable, starting with Diversity, test your hypothesis against a large number of situations to make sure that you are correct about your assumptions. Another important tactic would be to have a larger group, the more times the experiment is repeated with the same result the more valid of an experiment it becomes. Being able to repeat the experiment is a good sign that the information you gathered from it is reliable. One trap that you can fall in with experiments is affirmative bias, this is the process of trying to prove yourself right, instead of wrong. When designing an experiment it is more helpful to prove yourself wrong and fail.

Data Collection

Data collection is one of the last steps in the process of running an experiment. This step is about writing down what you have gathered and interpreting what it means. In the collection of data you want to be very careful about the information you take down and its accuracy. This data can then be shown in a number of ways for example a list, or chart. This allows the information you gathered to be easier to work with understand.

My Experiment

This experiment is to test the preference that cats have on dry food vs. wet food.

Hypothesis: My hypothesis is that the cats will prefer the wet food to the dry. I am making this guess on the basis of previous experience and knowing that wet food is more healthy.

Independent Variable: The independent variable in this case is the food, we will be switching out the types of food from dry food to wet and observing the cat's choice of food.

Dependent Variable: For this experiment the dependent variable is the cat’s eating. Depending on the food provided this variable may see change.

Control vs. Experimental Group: The control group consists of the cats being fed only dry food. The experiment is to see how much of the food is consumed in the first 10 minutes. The other control group had the same group of cats fed wet food. One more trial as the experimental group gives the cats both food types and they eat which ever one they would like this is to show the preference of the average cat.

Constants: The cats themselves are the same, we use the same bowls as before and the same time limit. The cats would not have eaten 8 hours before hand in each case and the amount of food stayed consistent.

Ways to prove validity and reliability: The first and easiest thing to do is repeat the trial, doing twice gives more data which is better. Increasing the number of cats as well as the diversity of cats. Cats from homes who feed them wet or dry food.

Data Collection:

In the trials we gathered 200 cats and a generic dry and wet food, each ct was not fed within 8 hours of the experiment. Within 10 minutes the cats are to eat as much as they want and a chart will be kept to see how much the cats ate.

Control

Trial 1 (Dry food)

87% of food was consumed

Trial 2 (wet food)

92% of food was consumed

Experimental

Trial 1 (both)

82% only wet

13% both

5% only dry

Trial 2 (both)

84% only wet

12% both

4% only dry