Under what circumstances can a very small treatment effect be statistically significant? If the sample size is small and the sample variance is large. If the sample size is big and the sample variance is small.
Under what circumstances will the distribution of sample means be normal quizlet?
Under what circumstances is the distribution of sample means normal? If the sample size is greater than 30. If the population is normal or if the sample size is greater than 30. It is always normal.
When choosing a smaller alpha level a researcher risks what?
The smaller the alpha level, the smaller the area where you would reject the null hypothesis. So if you have a tiny area, there’s more of a chance that you will NOT reject the null, when in fact you should. This is a Type II error.
Which set of sample characteristics is most likely to produce a significant value for the independent measures t statistic quizlet?
As sample variance increases, what happens to measures of effect size such as r^2 and Cohen’s d? They tend to decrease. Which set of sample characteristics is most likely to produce a significant value for the independent-measures t statistic? A large mean difference and small sample variance.
Under what circumstances will the distribution be normal?
If a variable has a skewed distribution for individuals in the population, a larger sample size is needed to ensure that the sampling distribution has a normal shape. The general rule is that if n is more than 30, then the sampling distribution of means will be approximately normal.
Under what circumstances will the distribution of the sample mean be normal?
To summarize, the distribution of sample means will be approximately normal as long as the sample size is large enough. This discovery is probably the single most important result presented in introductory statistics courses. It is stated formally as the Central Limit Theorem.
Is alpha The significance level?
The significance level, also denoted as alpha or α, is the probability of rejecting the null hypothesis when it is true. For example, a significance level of 0.05 indicates a 5% risk of concluding that a difference exists when there is no actual difference.
How do you determine level of significance?
To find the significance level, subtract the number shown from one. For example, a value of “. 01” means that there is a 99% (1-. 01=.
What must be done to decrease the chances of Type I and type II errors?
You can decrease the possibility of Type I error by reducing the level of significance. The same way you can reduce the probability of a Type II error by increasing the significance level of the test.
What is the disadvantage of using a smaller alpha level?
Lower values of α make it harder to reject the null hypothesis, so choosing lower values for α can reduce the probability of a Type I error. The consequence here is that if the null hypothesis is false, it may be more difficult to reject using a low value for α.
Which of the following correctly describes the effect that decreasing sample size and decreasing the standard deviation have on the power of a hypothesis test?
Which of the following correctly describes the effect that decreasing sample size and decreasing the standard deviation have on the power of a hypothesis test? A decrease in sample size will decrease the power, but a decrease in standard deviation will increase the power.
When alpha decreases would increase?
When you do this, alpha decreases, power (1 – beta) decreases, and beta increases. On the other hand moving that same vertical line to the left increases alpha, increases power, and decreases beta. To put it another way, increases in alpha increase power and decreases in alpha decrease power.
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