Normal Disribution

• Normal Distribution - It is the most important and widely used distribution in Statistics.
• Normal distribution is a set of well balance or distributed set of data.
• Normal Distribution - Commonly called Bell curve and Gaussian Curve
• Normal Distribution is discovered by Abraham de Moivre and finalized by Carl Friedrich Gauss
• The value of the standard deviation is 1 and the mean is 0 (zero)
• Data of Standard Normal Distribution is converted into Z-Scores.
• Z-score - refers to the data inside of the normal curve
• Probability - measurement of chance of an event to occur.
• Experiment - the process or activity of obtaining the possible events
• Events - is the outcome or result of an experiment
• Sample space - is the list all possible outcomes of an experiment
• Complementary of Events - refers the area excluding the possible E event
• Mutually Exclusive Events - events are not possible to happen simultaneously / walang pagkakapareho
• Non-mutually exclusive events - Events are possible to happen together / may kakapareho
• Inferential - is a branch of statistics that focuses on the formulation of conclusion.
• Conclusion - is a statement that is accepted and proven true and valid.
• Hypothesis - Tentative answer to the given question about the characteristic of the population or the subject that aimed to analyze.
• Null Hypothesis - Type of hypothesis that is Expressed by HO and the Idea of neutrality of the variables.
• Null Hypothesis - “there no significant difference/ effect / relationship”
• Alternative Hypothesis

  • Expressed by Ha or Hi
  • Expressed in affirmative form
  • “there is significant difference/relationship/ effect”
• Non-Directional- Type of Alternative Hypothesis that is no direction of change
• Directional - Type of Alternative Hypothesis that is Direction of change
• Level of Significance (α)

  • is the allotted percentage of mistake while making the decision about the hypothesis.
  • Its value ranges from 1% to 10%.
• Level of Confidence

  • is the contrary of the level of significant.
  • It is the percentage of accuracy and reliability that the decision is valid or correct.
  • In symbol it is expressed as 1- α.
• Critical Region or Rejection Region

  • is the region located at the far end of the normal curve.
  • This region is very important in formulating decision about the null hypothesis.
  • The area of the critical region is simply the value of the chosen level of significance
• Acceptance Region

  • is the other portion in the normal curve.
  • Its area is the same with the level of confidence.
• Critical Value - is the number that serves as the boundary line

  between the acceptance and critical regions.
• Testing of Hypothesis

  • Is the process of evaluation of the hypothesis.
  • needed to be able to know if the formulated statement is really correct or not.
• Accept HO - If the value of the test stat falls on the ACCEPTANCE REGION of the curve
• Reject Ho - If the value of the test stat falls on the REJECT/CRITICAL REGION of the curve
• Reject Ho - P-value is less than the level of significance
• Accept Ho - P-value is greater than or equal to the level of significance
• One-tailed testing - is the nature of the testing process if the

  alternative hypothesis directional is used.
• two-tailed testing - is the nature of the testing process if the

  alternative hypothesis – non directional is used.
• TEST STATISTICS

  • It refers to the formulas in the testing of hypothesis
  • It summarizes the characteristics of the sample that are relevant in the testing process.
• Parametric Tests

  • normally distributed
  • Data is interval and ratio.
  • uses of the values of mean, standard deviation, variance, etc.,
• Non-parametric Tests

  • it is also called distribution-free methods
  • not normally distributed.
  • nominal or ordinal scale.
• Standard Error - measures how far is the sample statistics from the

  population statistics.
• Confidence Interval - It refers to the estimated possible range values

  where in the the parameters of the population falls using the sample.