Exam 9: Introduction to the T Statistic

A researcher selects a sample from a population with a mean of  = 40 and administers a treatment to the individuals in the sample.If the treatment is expected to decrease scores,which of the following is the correct statement of the null hypothesis for a one-tailed test?

A sample of n = 16 scores has a mean of M = 58 with SS = 960.Use the sample to construct the 90% confidence interval for µ.

With α = .05,what is the critical t value for a one-tailed test with n = 15?

If other factors are held constant,how does sample size influence the likelihood of rejecting the null hypothesis and measures of effect size such as r² and Cohen's d?

If other factors are held constant,what is the effect of increasing the sample variance?

As the sample size is increased,the distribution of t statistics becomes flatter and more spread out.

A sample of n = 16 scores with a sample variance of s² = 64 has an estimated standard error of 4 points.

The t distribution for df = 4 is flatter and more spread out than the t distribution for df = 20.

If other factors are held constant,the bigger the sample is,the greater the likelihood of rejecting the null hypothesis.

If two samples are selected from the same population,under what circumstances will the two samples have exactly the same t statistic?

If a researcher is using a t statistic to test a null hypothesis about a population,what information is needed from the population to calculate the t statistic?

A researcher conducts a hypothesis test using a sample of n = 20 from an unknown population.What is the df value for the t statistic?

Which of the following samples will have the smallest value for the estimated standard error?

On average,what value is expected for the t statistic when the null hypothesis is true?

A researcher selects a sample from a population with  = 30 and uses the sample to evaluate the effect of a treatment.After treatment,the sample has a mean of M = 32 and a variance of s² = 6.Which of the following would definitely increase the likelihood of rejecting the null hypothesis?

A sample of n = 16 scores has a mean of M = 65 and an estimated standard error of 2 points.What is the sample variance?

If the 90% confidence interval for µ is from 40 to 50,then the sample mean is M = 45.

The results of a hypothesis test are reported as follows: t(15)= 2.70,p < .05.Based on this report,how many individuals were in the sample?

If the null hypothesis states that  = 70 and a researcher obtains a sample with M = 73 and s² = 9,then Cohen's d = 0.33.

In a hypothesis test,a large value for the sample variance increases the likelihood that you will find a significant treatment effect.