Exam 6: Making Sense of Statistical Significance:decision Errors, Effect Size, and Statistical Power

A way to increase effect size is to change the procedures of a study so that the __________ of the population is decreased.

Effect size is an important tool for making sense of research results because it

When the known and comparison populations overlap by 85%,the effect size is __________.

The degree of separation between populations due to the independent variable is one way of understanding __________.

Setting the significance level at .20 increases the chance of

An organizational psychologist conducted a study to see whether upgrading a company's older computer system to newly released,faster machines would cause an increase in productivity from the current average of 120 units with a standard deviation of 20.The new system will be tested in a single department with 45 employees.The company has decided that an increase of less than 10 units will not justify purchasing the new system. a.What is the predicted effect size for an increase of 10 points? b.Explain the logic of what has been done. c.Advanced topic: Sketch the distributions involved. d.Advanced topic: If the data are analyzed at the .01 significance level,what will be the power of the study? e.Advanced topic: Explain your answer to a person who understands hypothesis testing with means of samples,but who is not familiar with power.

Using the .01 level of significance instead of the .05 level increases the chance of making a(n)__________.

Power is the probability that

While no research hypothesis is ever definitely false,failing to reject the null hypothesis in a study that has a high level of power allows one to

If a study conducted at the .05 significance level has 80% power

The statistical method currently used to combine the results of multiple studies is

If power is 45%,then beta equals __________.

A statistic that combines two of the main influences on power,the expected difference between populations and the population standard deviation,is __________.

According to Cohen,a good general rule for when it is worthwhile to conduct a study is when power is at least __________%.

The alpha level is

The smaller the population standard deviation,the greater the power,because the distributions of means based on the known and comparison populations are both __________.

The effect size of a study is a good indicator of its practical importance because,unlike statistical significance,it is not affected by __________.

If an experimenter CANNOT manipulate the effect size of an experiment to increase power,the aspect of a study that can usually be changed easily to increase power is

In actual practice,the usual reason for determining power before conducting a study is

Increasing sample size __________ power.