Hypothesis
The statement that there is no difference or no relationship between variables
What is the null hypothesis (H0)?
This is the name for a symmetrical, bell-shaped distribution
What is a normal curve?
This is the probability that your results occurred by chance alone
What is a p-value?
This test is used to compare a sample mean to a known population mean
What is a one-sample t-test? What is a one-sample z-test?
This test is used to compare the means of two different groups
What is a two-sample t-test? What is an independent-samples t-test?
The point at which you decide to reject or fail to reject the null hypothesis
What is the level of significance (or alpha level)?
In a normal distribution, the mean, median, and mode are all located here
What is at the center?
The alpha level, typically set at 0.05, represents the probability of committing this type of error
What is a Type I error?
The value you compare your calculated (observed value) t-statistic to in order to make a decision about the null hypothesis
What is the critical t-value?
The term for two samples where the participants in one group have no relationship to the participants in the other
What is independent samples?
Rejecting a true null hypothesis
What is a Type I error?
The percentage of scores that fall between -1 and +1 standard deviations from the mean in a normal distribution
What is 68%?
This type of error occurs when you fail to reject a null hypothesis that is actually false
What is a Type II error (or beta error)?
As your sample size increases, this happens to the degrees of freedom
What is it increases?
When you have unequal sample sizes in an independent-samples t-test, you must assume that the variances of the two groups are either equal or not equal; this is called the assumption of…
What is homogeneity of variance? What is equality of variance?
The probability of obtaining your results if the null hypothesis is true
What is the p-value?
The value that describes a score's distance from the mean in standard deviation units
What is a z-score?
While statistical significance is about rejecting the null hypothesis, this term refers to whether the result has a meaningful impact in the real world
What is practical significance?
The type of hypothesis where you predict that your sample mean will be different from the population mean, but you don't specify the direction
What is a two-tailed hypothesis?
The name of the statistic that indicates how large your effect is, independent of sample size.
What is effect size (or Cohen's d)?
The type of test you should use if you have a specific directional prediction, such as "greater than" or "less than"
What is a one-tailed test?
A distribution with a long tail extending to the left is called this
What is negatively skewed?
The amount of power a statistical test has to correctly reject the null hypothesis when it is false
What is power?
The smaller your p-value, the more likely you are to do this
What is reject the null hypothesis?
When you have a very small effect size but a large sample, your results can be statistically significant but not necessarily this.
What is practically significant or meaningful?