Self-contained binomial hypothesis testing. Specifically 2-tailed test at a confidence interval of 95%.

BinomialHypothesisTest.scala

object BinomialHypothesisTest {
  
  def tTestBinomial(p1:Double, n1:Int, p2:Double, n2:Int): TtestRes = {
    val k =  (n1*p1 + n2*p2) / (n1 + n2).toDouble
    val z = (p1 - p2) / math.sqrt( k*(1 - k) * (1 / n1.toDouble + 1 / n2.toDouble) )
    if(z > scoreForTwoTailed95CiPval)
      RejectNull
    else
      FailToReject
  }
  
  private[this] val scoreForTwoTailed95CiPval = 1.96

  sealed abstract class TtestRes

  case object RejectNull extends TtestRes { 
    override val toString = "Reject the null hypothesis."
  }

  case object FailToReject extends TtestRes { 
    override val toString = "Fail to reject the null hypothesis."
  }
}

Resources:
[1] https://en.wikipedia.org/wiki/Statistical_hypothesis_testing
[2] http://stats.stackexchange.com/questions/113602/test-if-two-binomial-distributions-are-statistically-different-from-each-other
[3] http://www.ats.ucla.edu/stat/mult_pkg/faq/general/tail_tests.htm