Exam #2 Study Guide
Exam #2 Study Guide Psy 202
Popular in Elementary Statistics
Popular in Psychology (PSYC)
This 6 page Study Guide was uploaded by Jessica Crump on Friday October 14, 2016. The Study Guide belongs to Psy 202 at University of Mississippi taught by Dr. Melinda Redding in Fall 2016. Since its upload, it has received 38 views. For similar materials see Elementary Statistics in Psychology (PSYC) at University of Mississippi.
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Date Created: 10/14/16
Exam 2 Study Guide: Ch. 5-‐9 Fill in the Blank 1. When not everyone who is asked to participate in a study agrees to participate the population becomes less represented. This is referred to as a _____________________. 2. A distribution of means is referred to as _____________________. 3. _____________________ refers to a range of scores built around a sample value that is assumed to contain the population mean. 4. When the proportions of the variables, in a population are accurately reflected in the sample, we call the sample _____________________. 5. Sampling error reflects discrepancies between values of the _____________________ and the _____________________ due to random factors. 6. A sample that gives every case in the population an equal chance of being selected, thus, does not guarantee a representative sample _____________________. 7. The Central limit theorem tells us three things: a. b. c. 8. _____________________ compares a sample mean to a population mean with a known population standard deviation. 9. The hypothesis that goes against the research question; says that there’s no effect is the _____________________. 10. When the null hypothesis is correctly rejected it is referred to as _____________________. 11. The name for the regions of the distribution that result in the rejection of the null _____________________. 12. What are the three things that can be done to increase power? a. b. Exam 2 Study Guide: Ch. 5-‐9 c. 13. _____________________ says that the theoretical population is different from your true population mean. 14. The amount of impact that the explanatory variable has on the outcome variable is referred to as _____________________. 15. A single sample t test is used to compare a sample mean to population mean when the _____________________ of the _____________________ is unknown. 16. When cases selected for one sample are connected to the cases selected for another the appropriate test is a(n) _____________________. 17. Put the following steps of hypothesis testing in order 1-‐6 (1 being the first step and 6 being the last step). a. Interpretation ___ b. Decision rules ___ c. Test ___ d. Assumptions ___ e. Calculation ___ f. Hypothesis ___ True or False If it’s false, add or replace the word(s) needed to make it correct. 1. Type 1 error occurs when the null hypothesis is rejected and there really was a treatment effect. _____________________ 2. When the standard deviation of the population is not known, the standard deviation of the sample can be used to estimate the standard error of the mean. _____________________ 3. The alpha level refers to the proportion of the sampling distribution in between the tails. _____________________ 4. When you increase your alpha level, you increase your type I error and decrease your type II error. _____________________ Exam 2 Study Guide: Ch. 5-‐9 5. In APA format, p < .05 means that the null is rejected and the alpha level is .05. _____________________ 6. The degrees of freedom (df) are equal to the degrees of freedom of the sample variance. _____________________ 7. As the sample size decreases, the sample variance more closely resembles the population variance. _____________________ 8. Cohen’s D tells how many standard deviations apart the means are. _____________________ 9. The alternative hypothesis is what is tested. _____________________ 10. The independent samples t test is used to compare the means of two independent samples. _____________________ 11. With independent samples t tests, the larger samples affect the variance; that’s why they are pooled. _____________________ 12. Within-‐subjects tests have 1 sample, 2 means, and no independent variable. _____________________ 13. Repeated measures tests have 2 samples and 2 means. _____________________ 14. All the t test formulas have a mean difference in the numerator and variance in denominator. _____________________ 15. Paired samples t tests have more power than independent samples t tests. _____________________ 16. The null hypothesis goes with the research question. _____________________ 17. As degrees of freedom increase, the values for the critical regions decrease. _____________________ Exam 2 Study Guide: Ch. 5-‐9 Helpful Tips • If you don’t know the population standard deviation (s), it’s a t test. • If the null is rejected, you can calculate the effect size. • An equal sign of some kind (≥,≤,= ) will always be in the null hypothesis (H0). • APA format – [t(15) = -‐1.333, p >.05] o t – tells it’s a t test o 15 – tells us the degrees of freedom o -‐1.333 – tells t obs o p </> .05 – tells the alpha level and whether or not the null was rejected § p < .05 – means the null was rejected § p > .05 – means failed to reject the null • When making the hypotheses for a one tailed test, it’s easier to start with the alternative hypothesis because it goes along with the research question. From there, you know that the null will just be the opposite. • I’m putting a flow chart I made for deciding which test to use on the page before the answers. • Dr. Redding mentioned that a few older topics like inferential statistics vs. descriptive statistics, and research designs would be on the test so brush up! Symbols • H 0 – null hypothesis • H 1 – alternative hypothesis ▯ • sM – standard error of the means (▯ ) • µ – sampling distribution of means M • df – degrees of freedom • s or ▯ – (estimated) standard error of the mean M ▯ • d = cohen’s d 2 • s p – pooled variance • D – difference scores (x –1 x 2 • M – mean difference (i.e. mean of difference scores for a sample) D ▯ ▯ • S MD r – standard error of the mean difference ▯ Exam 2 Study Guide: Ch. 5-‐9 Population standard deviation ( )? No Yes Is there more than one population mean z test (µ)? No Yes Single sample t Are the sample sizes test equal for all samples? Yes No Are the Cases paired or Independent samples t test returning/repeatdly measured? No Yes Independent Paired samples t samples t test test Exam 2 Study Guide: Ch. 5-‐9 Answers 1. Self-‐selection bias 8. True 2. Sampling distribution 9. False, alternative should be null 3. Confidence interval 10. False, samples should be 4. Representative populations 5. Sample and the population 11. True 6. Random sample 12. True 7. a. n is large, sampling distribution is 13. False, 2 should be 1 normal, b. sample distribution mean 14. False, variance should be standard is the same as the population mean error c. the standard error can be 15. True calculated ???? ▯ ▯ 16. False, null should be alternative ▯ 17. True 8. Single sample z test 9. Null hypothesis 10. Power 11. Critical regions 12. a. increase sample size, increase alpha level, or use a one-‐tailed test 13. Alternative hypothesis 14. Effect size 15. Standard deviation, population 16. Paired samples t test 17. a. 6 b. 4 c. 1 d. 2 e. 5 f. 3 True/False 1. False, there really wasn’t a treatment effect. 2. True 3. False, delete the word between (the alpha level refers to the proportion of the sampling distribution in the tails) 4. True 5. True 6. True 7. False, decreases should be increases
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