Please help explain the difference between the two given results

Two different researchers, Sarah and Joel, are studying the effects of video game violence on IQ scores in teenage boys. Sarah fails to find significance, while Joel succeeds in finding significance. The population mean for IQ scores is u = 100 and they each ended up with a sample mean of IT = 103. Based on the information below and using concepts discussed in class, provide an explanation for the difference between Sarah's results and Joel's results. Sarah Joel & = 100 u = 100 15 o = 15 I = 103 I = 103 n = 25 n = 4.000 a = 0.05 a = 0.05