Posted by Kailey on Tuesday, May 10, 2011 at 4:13pm.
You can find standard error by taking the standard deviation divided by the square root of the sample size.
Critical values determine whether or not to reject the null hypothesis. If you have an observed test statistic (calculated from a formula) that exceeds a critical value from a table, then you have to reject the null hypothesis and accept the alternative hypothesis. If the observed test statistic does not exceed the critical value from a table, then you fail to reject the null hypothesis. For example, how do you translate a significance level of 0.05 into a critical value? It depends on the type of test you are doing. For a one-tailed test, you don't split the value. For a two-tailed test, you split the 0.05 into 0.025 and 0.025 for both tails of the distribution curve (a two-tailed test is like a confidence interval in that respect). If you use a z-table for a one-tailed test at 0.05 level of significance (meaning the alternative hypothesis is showing a specific direction like "less than" or "greater than" in its statement), then you will have a critical value of z = -1.645 or it could be z = 1.645, depending on the direction. This will determine where you "draw the line" to reject the null hypothesis. If you use a z-table for a two-tailed test at 0.05 level of significance (meaning the alternative hypothesis is showing no specific direction and uses "does not equal" in its statement), then you will have a critical value of z = + or - 1.96 (meaning either tail of the distribution curve). For example, if you had a test result of z = +2.00, then you would have exceeded the positive critical value of +1.96 for this particular test result and the null hypothesis would be rejected in favor of the alternative hypothesis.
I hope this will help.
Related Questions
Statistics(Please help) - the problem asks to complete an ANOVA table and report...
statistics - I am not understanding this last portion of my statistics class. I ...
statistics - Using the z table, find the critical value (or values) for an = 0....
statistics - A researcher has collected statistics pretest scores for students ...
statistics - Using the z-table (Table E) find the critical value (or values) for...
statistics - What is the critical value for 0.04, left tailed test? I dont know ...
statistics - 5. The table below shows Psychology exam scores, Statistics Exam ...
I am really in need of someone help! Please - A researcher has collected ...
PLEASE HELP ME!!! - A researcher has collected statistics pretest scores for ...
math - The probability that Luis will pass his statistics test is 0.37. Find the...
For Further Reading
