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Two Means - Known Variance definitions

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  • Population Standard Deviation
    A fixed measure of spread for an entire group, used directly in calculations when its value is known.
  • Sample Mean
    An average value calculated from a subset of data, representing the central tendency of that group.
  • Z-Test
    A statistical method used to compare two averages when the variability of the populations is already established.
  • Null Hypothesis
    A starting assumption stating there is no difference between two group averages.
  • Alternative Hypothesis
    A claim suggesting a difference exists between two group averages, often in a specific direction.
  • Alpha Level
    A threshold probability used to decide if evidence is strong enough to reject the initial assumption.
  • P-Value
    A calculated probability indicating how likely observed results are if the initial assumption holds true.
  • Independent Random Samples
    Two groups of data selected so that each value is chosen by chance and does not influence the other group.
  • Normality
    A condition where data follows a bell-shaped curve, supporting valid statistical inference.
  • Sample Size
    The number of observations collected from a group, affecting the reliability of statistical results.
  • Z Score
    A standardized value showing how far a sample difference is from zero, measured in units of spread.
  • Test Statistic
    A calculated number summarizing sample data to help decide between competing claims.
  • Two-Sample Z-Test Function
    A calculator or software feature that automates the process of comparing two averages with known variability.
  • Critical Value
    A cutoff point that determines whether the observed result is unusual enough to challenge the initial claim.
  • Hypothesis Test
    A structured process for using sample data to evaluate claims about population averages.