Question

Please thoroughly explain your answer to the following question:

Suppose that two people measure the earth’s magnetic field in different locations, and they will not obtain exactly the same answers. How will you decide whether the differences are statistically-significant?

Answer 1

The difference between two groups is statistically significant if it can not be explained by chance alone.

• Usually, statistical significance is determined by calculating the probability of error (p value) by the t ratio.
• The difference between two groups (such as an experiment vs. control group) is judged to be statistically significant when p = 0.05 or less.
  • At p= 0.05, the differences between the two groups have only a 5% probability of occurring by chance alone.
  • At p= 0.01, the differences between the two group have only a 1% probability of occurring by chance alone.