GCSE Biology

HI, validity relates to how reliable / correct the experiments results are such as is the experiment useful to what i am investigating or are you measuring what you are meant to measure

To improve validity = Increase random samples to avoid bias , have more control variables , more accurate measuring equipment ( a computer to reduce likelihood of human error)

To reduce validity = would be exact opposite in which the results are more likely to be biased and only completing the experiment once.

Hope this helps