Exam II Lecture 13 Stats 3 Flashcards
Variation of the sample mean depends on the sample….
Size!
As n increases the distribution of the sample mean has a smaller spread.
What is the standard error of teh mean?
Reflects the uncertainty of the mean estimated from a sample.
What is the interval estimator
Basically the same as the confidence interval.
It gives us a range of values that are most likely to contain the population mean.
What is the margin of error?
Confidence interval is expressed as the mean + the margin of error!!
What is a nondirectional research hypotheses?
States that there is a difference between groups but doesnt specify the directon.
Ex: there is a difference between genders regarding number of times per week that ice cream is consumed.
What is a directional research hypothesis?
States there is a difference and specifies the direction.
The average number of times that men eat ice cream per week is greater than the average number of times that women each ice cream per week.
What is the test statistic?
A value used in making a decision about the null hypothesis.
found by converting the sample statistic to a score with the assumption that the null hypothesis is true.
What is the p value?
The probability value.
The probability of getting a value of the test statistic that is at least as extreme as the one representing the sample data, assuming the null hypothesis is true.
Based on the p value, when would you reject the null hypothesis?
If the p value is less than the alpha value you reject the null hypothesis.
If it is larger than the alpha value you cannot reject the null hypothesis.
What is the critical region?
The set of all values of the test statistic that causes us to reject the null hypothesis.
What is the critical value?
Any value that separates the critical region (where we reject the null hypothesis) from the values of the test statistic that do not lead to the rejection of the null hypothesis.
What is a type I error? **
Mistake of rejecting the null hypothesis when it is actually true!!
Alpha is used to represent the probability of a type 1 error.
Remember if p value is > than alpha you cannot reject the null hypothesis!!
What is a type II error?
The mistake of failing to reject the null hypothesis when it is actually false.
the symbol beta is used to represent the probablity of a type II error.
