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When population standard deviation is known, the z-score is used, when population standard deviation is unknown, the __ is used - Correct Answer t- score True/False Since t-scores are centered normally around the mean and form a bell-shaped curve, probabilities can be calculated to draw inferences about populations. - Correct Answer True ____ determine how well the t-distripution approximates the normal distribution of the z-scores. To calculate for any sample size, n-1 - Correct Answer Degrees of freedom (df) At distribution approximately resembles a normal distribution when n=___- Correct Answer n=12 T-testing for a one sample test is used when ___ - Correct Answer the population mean is known In a one sample test, state the possible Ho and Ha hypotheses - Correct Answer Ho: H = known population mean Ha: Ht > known population mean (right tailed) p< known population mean (left tailed) y # equal known population mean (two tailed) How to calculate df for one sample tests - Correct Answer n-1 For t-testing, you compute ___ based on a sample statistic rather than using a standard deviation based on a population parameter - Correct Answer standard error The __ is centered around the mean, extending to the left and to the right to include estimated standard error, sx. It provides a range of values that would likely contain the population mean at a given alpha level. - Correct Answer confidence intervals A__ sample t-test uses 2 samples from different groups, like independent measure design or between-subjects design. - Correct Answer independent A__ sample t-test uses 2 samples from the same group, like repeat measure design, within subjects design, or matched pairs study. - Correct Answer paired sample t-test A____ design t-test uses different samples from different populations, for example men and women - Correct Answer independent measure design A__ design t-test uses participants randomly assigned to a treatment group each with its own condition and the researcher looks for whether or not there is a significant difference in the mean between the two treatments. - Correct Answer between-subjects design A__ design t-test is a dependent, two-sample study that uses the same participants under each treatment, for example mean exam scores before and after spring break. - Correct Answer repeat measure design A __ design is when a researcher is looking to see if there is any difference between the scores within the same group of participants. - Correct Answer within subjects design A__ design combines independent measures and repeated measures concepts, where participants in two study groups are matched based upon specific variables/criteria that may be relevant to the study. After treatment is applied to both groups, the results are compared. - Correct Answer matched pairs study For independent samples t-tests, the possible hypotheses are: - Correct Answer Ho: y1=y2 (population means are equal) Ha: 1#y2 (population means are not equal) Ho: y1-"2=0 (no difference between pop means) Ha: 1-240 (there is a difference between pop means) How to calculate df for independent sample t-tests: - Correct Answer dftotal: n1 + n2 -2 Smaller degrees of freedom __ the critical region - Correct Answer increase If a researcher states in the alternative hypothesis that y is greater than the claimed value, what type of test would be performed? - Correct Answer Right- tailed In what type of experimental design is an assessment administered before and after a treatment condition with the same participants? - Correct Answer Pre/post-test design If a researcher administers the same medication to a group of teenagers and a group of adults, what type of design is this? - Correct Answer Independent samples design 
