A random sample of 100 people from City A has an average IQ of 120 with a SD of 18. Independently of this, a random sample of 150 people from City B has an average IQ of 116 with a SD of 15. Are residents of City A smarter on average? Make a z-test of the difference in average lQs; the null hypothesis is that there is no difference. Round your values to three decimal places.
If the null is right, the expected value of the difference between average IQs in each sample is and the standard error of this difference is estimated to be
The observed difference is
The test statistic is
The P-value is approximately