Hypothesis Testing Concepts and Z Scores

The video tutorial explains the one sample Z test, a fundamental inferential statistics test. It covers the empirical rule and how it relates to the normal curve. An example is provided where a medication's effect on IQ is tested using a sample of 30 participants. The tutorial outlines six steps for conducting a Z test: defining hypotheses, stating the alpha level, decision rule, calculating the test statistic, stating results, and drawing conclusions. The example concludes with rejecting the null hypothesis, indicating the medication significantly affects intelligence.

What percentage of scores fall within one standard deviation of the mean in a normal distribution?

• 99.7%

• 50%

• 68%

• 95%

In the given example, what is the null hypothesis regarding the population mean IQ?

• The mean IQ is 140.

• The mean IQ is not 100.

• The mean IQ is 115.

• The mean IQ is 100.

What is the standard deviation of the population in the given example?

• 25

• 20

• 15

• 10

What is the significance level (alpha) commonly used in hypothesis testing?

• 0.01

• 0.05

• 0.50

• 0.10

Which of the following is NOT a step in conducting a Z test?

• Calculating the test statistic

• Conducting a survey

• Stating the decision rule

• Defining the hypotheses

What is the purpose of setting an alpha level in hypothesis testing?

• To calculate the Z score

• To control the probability of a Type I error

• To determine the sample size

• To define the null hypothesis

Which of the following is a characteristic of a two-tailed test?

• It only considers decreases in the mean.

• It does not consider changes in the mean.

• It only considers increases in the mean.

• It considers both increases and decreases in the mean.

What is the calculated Z score in the example provided?

• 0.05

• 2.58

• 1.96

• 14.60

If the calculated Z score is greater than 1.96, what decision is made regarding the null hypothesis?

• Increase the sample size

• Decrease the alpha level

• Reject the null hypothesis

• Accept the null hypothesis

What does rejecting the null hypothesis imply in the context of the medication's effect on IQ?

• The medication has no effect on IQ.

• The sample mean is equal to the population mean.

• The test was inconclusive.

• The medication significantly affects IQ.