Question: how would you go about doing your experiments and are there any I can do at home?

Annis Richardson answered on 23 Mar 2023:

There are lots of experiments you can easily do at home.
For example perhaps you are interested in finding out what is important for plants to grow.

Every experiment you run should test a hypothesis e.g. I hypothesise that growing beans in the dark will make them tall.
To test this hypothesis you need to design an experiment that can produce data that rigorously tests the effect of growing beans in the dark vs normal conditions.

Start by writing out all of the conditions that your bean seed is exposed to that could affect how it grows, these are called variables. Variables could include: growing medium (e.g. soil, cotton wool, paper towel, etc), light, temperature, size of seed, water, length of time.
Then pick one variable that you are going to change to test your hypothesis – in this case we would pick light. All other variables would need to be kept the same between your samples otherwise you won’t be able to tell if light affects bean growth.

Now you design your experimental set-up. Start with your controls, these are samples that you will compare your test to. For example in our growth experiment we would have a plant grown under normal light conditions (perhaps on a windowsill). So maybe a bean seed that is 2g put on a cotton wool bud with 10mL of water, in a plastic cup, and put at room temperature on the kitchen side.
Then our test sample will vary in only one way to the control- we would have a 2g bean seed on a cotton wool bud with 10mL water in a plastic cup, put on the kitchen side at room temperature but wrapped entirely in black card to stop the light getting in. Because there can be variation between samples you would have at least 3 replicates of each sample to make sure that you haven’t accidentally got a weird plant. These are called biological replicates.

Then plan how you are going to collect your data. In our case we could wait the same amount of time, then measure our plants, or we could measure our plants every day. This should be measured in the same way for all of the samples.

Once everything is planned we can run the experiment. Keep notes on how you run the experiment as you run it because sometimes you do things slightly differently. For example you might need to add more water to the control samples on day 3 and you would also need to add the same to the test samples.

Once complete you analyse the data, and then you run the experiment 2 more times in the same way to make sure that the data is reproducible. These are called technical replicates.

Then you analyse all the data and see if you can accept or reject your hypothesis. There are lots of different statistical tests you can do to say how confident you are in your conclusions. Based on this you then form a new hypothesis and design a new experiment to test this one.