Exam 8: Tests for Significance: Z-Tests and One-Sample T-Tests

You want to compare a sample of n = 49 to a population where  = 18. If x̄ = 21 and s = 3.5, what is the value of the standardized effect size?

You want to demonstrate that a sample of n = 36 has a lower mean than a population where  = 22. If x̄ = 25 and s = 8, what is the correct decision?

A difference score is an example of a standardized effect size.

If you conduct a left-tailed t-test with a sample size of 101 and find that t = 2.58, then p < .05.

You draw a sample of n = 21 from a population where  = 3 and x̄ = 6 and s = 5, t = 2.75.

You want to demonstrate that a sample of n = 16 has a greater mean than a population where  = 9. If x̄ = 6 and s = 7, what is the critical value?

If you want to know the range of likely values for a sample mean given a particular population mean, you should conduct a z-test.

Once you've calculate an obtained test statistic, how do you determine if it is statistically significant?

Effect size calculations provide an estimate of the real-world value of a particular finding.

You want to compare a sample of n = 64 to a population where  = 10 and  = 30. If x̄ = 27, what is the value of the unstandardized effect size?

You want to compare a sample of n = 9 to a population where  = 6. If x̄ = 5 and s = 3, what is the value of the test statistic?

Weekly salary Weekly expenses 543 486 436 410 637 523 430 486 527 477 586 361 396 597 657 321 463 492 726 414 For the following questions: -In the population, we'd expect Weekly Salary to have a mean of 621, but you want to know if your sample comes from a different population. 1)State the research question. 2)State the hypotheses. 3)State the critical value. 4)Provide the formal test of the hypothesis. 5)State the confidence interval. 6)Is an effect size calculation appropriate? How do you know? If yes, calculate both a standardized and unstandardized effect size. 7)State all appropriate conclusions.

Weekly salary Weekly expenses 543 486 436 410 637 523 430 486 527 477 586 361 396 597 657 321 463 492 726 414 For the following questions: -In the population, we'd expect Weekly Expenses to have a mean of 525, but you want to know if your sample comes from a different population with a lower mean. 1)State the research question. 2)State the hypotheses. 3)State the critical value. 4)Provide the formal test of the hypothesis. 5)State the confidence interval. 6)Is an effect size calculation appropriate? How do you know? If yes, calculate both a standardized and unstandardized effect size. 7)State all appropriate conclusions.

If you run a two-tailed one-sample t-test where n = 12 and find that t = 2.57, you should reject the null.

You collect a sample of n = 31 and want to know if this sample is significantly different from the population. If  is known and  = .05, what is the appropriate critical value?

You do not need to know the population standard deviation to conduct a one-sample t-test.