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  3. Statistical Simulation in Python

Exercise

Power Analysis - Part I

Now we turn to power analysis. You typically want to ensure that any experiment or A/B test you run has at least 80% power. One way to ensure this is to calculate the sample size required to achieve 80% power.

Suppose that you are in charge of a news media website and you are interested in increasing the amount of time users spend on your website. Currently, the time users spend on your website is normally distributed with a mean of 1 minute and a standard deviation of 0.5 minutes. Suppose that you are introducing a feature that loads pages faster and want to know the sample size required to measure a 5% increase in time spent on the website.

In this exercise, we will set up the framework to run one simulation, run a t-test, & calculate the p-value.

Instructions

100 XP
  • Initialize effect_size to 5%, control_mean to 1 and control_sd to 0.5.
  • Using np.random.normal(), simulate one drawing of control_time_spent and treatment_time_spent using the values you initialized.
  • Run a t-test on treatment_time_spent and control_time_spent using st.ttest_ind() where st is scipy.stats, which is already imported.
  • Statistical significance stat_sig should be True if p_value is less than 0.05, otherwise it should be False.