How to calculate One Tail and Two Tail Tests For Hypothesis Testing.

statisticsfun
26 Jul 201104:33

Summary

TLDRThis tutorial explains one-tailed and two-tailed hypothesis tests, using a normal bell curve to illustrate the distribution of possible events. The population mean is denoted by the Greek letter 'mu', and the sample mean can vary within a certain range. A one-tailed test with a 95% confidence level implies a 5% chance (Alpha) of the sample mean falling in the rejection region. In contrast, a two-tailed test divides Alpha by two, placing 2.5% in each tail, ensuring a 95% chance of the sample mean falling within the acceptable range. Critical values for a 95% two-tailed test are ±1.96, while for a one-tailed test, they are ±1.645. The video promises more in-depth statistical insights.

Takeaways

  • 📊 The tutorial discusses one-tailed and two-tailed hypothesis tests, which are statistical methods to make inferences about a population.
  • 🔵 A normal bell curve is used to represent all possible events, with the population mean (μ) at the center.
  • 🌿 The sample mean (x̄) can vary and is represented within a green area on the bell curve, indicating its possible positions.
  • 🎯 In a one-tailed test with a 95% confidence level, there's a 5% chance (Alpha) that the sample mean will fall in the red, or rejection, region.
  • 🚫 The red area signifies the rejection region where the null hypothesis would be rejected if the sample mean falls within it.
  • 🔄 For a one-tailed test, the red area can be to the right or left of the mean, depending on the direction of the hypothesis.
  • 🔁 In a two-tailed test at a 95% confidence level, the 5% Alpha is split into 2.5% in each tail, providing a balanced test for deviations in either direction.
  • 🔢 The critical values for a two-tailed test at 95% confidence are ±1.96 z-scores, indicating the boundaries of the rejection regions.
  • 🔄 Switching back to a one-tailed test, the critical values adjust to ±1.645 z-scores, reflecting a higher probability of the sample mean being extreme in one direction.
  • 📚 The tutorial serves as an introductory lesson on hypothesis testing, with more advanced statistical concepts to be explored in subsequent lessons.

Q & A

  • What does the bell curve represent in the context of the tutorial?

    -The bell curve represents 100% of all possible events, with the population mean at the center.

  • What is the Greek letter used to denote the population mean?

    -The Greek letter used to denote the population mean is 'mu', which looks like a 'u' but is pronounced as 'me'.

  • What is the notation used for the sample mean in the tutorial?

    -The notation used for the sample mean in the tutorial is 'x-bar' (x̄).

  • What is the probability range for the sample mean in a one-tailed test with a 95% confidence level?

    -In a one-tailed test with a 95% confidence level, there is a 5% chance the sample mean will show up in the red area, which is also known as Alpha.

  • What is Alpha in the context of hypothesis testing?

    -Alpha is the probability of the sample mean showing up in the red area, which is also known as the rejection region. It can also be referred to as the P-value.

  • How is the red area distributed in a two-tailed test at a 95% confidence level?

    -In a two-tailed test at a 95% confidence level, the red area is split equally, with 2.5% on each tail (left and right).

  • What is the significance of the 2.5% on each tail in a two-tailed test?

    -The 2.5% on each tail represents the probability of the sample mean falling in the rejection region for a two-tailed test at a 95% confidence level.

  • What are the critical values for a two-tailed test at a 95% confidence level?

    -The critical values for a two-tailed test at a 95% confidence level are z-scores of -1.96 on the left and +1.96 on the right.

  • How do the critical values change for a one-tailed test?

    -For a one-tailed test, the critical value on the right is a positive 1.645, and on the left, it would be a negative 1.645.

  • What is the purpose of discussing one-tailed and two-tailed tests in the tutorial?

    -The purpose is to introduce and explain the concepts of one-tailed and two-tailed hypothesis tests, including their setup, probabilities, and critical values.

  • What does the term 'rejection region' refer to in hypothesis testing?

    -The 'rejection region' refers to the area of the distribution where the sample mean would lead to the rejection of the null hypothesis.

Outlines

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Mindmap

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Keywords

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Highlights

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Transcripts

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Related Tags
StatisticsOne-Tailed TestTwo-Tailed TestConfidence LevelCritical ValuesSample MeanPopulation MeanProbabilityStatistical AnalysisData Science