Question

1. What are descriptive statistics? Why do we need them in an experiment? 2. Following are two distributions of scores on a memory test. Find the mean, median, range, and variance of each group. Group 1: 5 3 6 1 8 3 3 2 1 5 Group 2: a. Mean b. Median c. Range d. Variance 3. Briefly outline the difference between the t-test for independent groups and the t-test for matched groups. 4. When do we use one-way analysis of variance? 5. a) What is a null hypothesis? b) You have run an experiment to test the effects of noise on motor dexterity. It was a three-group experiment. Your three conditions were a control condition with no noise, a low-noise condition, a high-noise condition. Your three-treatment means are different. State the null hypothesis for your experiment. 6. a) Jelly is going to run an experiment tomorrow in which her significance level will be p < .05. What does it mean? b) If she decides instead to use p < .01 as her significance level, will it be easier or harder for her to detect the effect of the independent variable? Why? 7. For each of the following examples explain whether the researcher has committed a Type 1 or Type 2 error and why. a) Dr. A rejects the null hypothesis although the independent variable had no effect. b) Dr. C rejects the null hypothesis when it falls. c) Dr. E does not reject the null hypothesis even though the independent variable had an effect. (Note: A type I error (false-positive) occurs if an investigator rejects a null hypothesis that is actually true in the population; a type II error (false-negative) occurs if the investigator fails to reject a null hypothesis that is actually false in the population.)

1. What are descriptive statistics? Why do we need them in an experiment?
2. Following are two distributions of scores on a memory test. Find the mean, median, range, and variance of each group.
Group 1:
5
3
6
1
8
3
3
2
1
5
Group 2:
a. Mean
b. Median
c. Range
d. Variance
3. Briefly outline the difference between the t-test for independent groups and the t-test for matched groups.
4. When do we use one-way analysis of variance?
5. a) What is a null hypothesis?
b) You have run an experiment to test the effects of noise on motor dexterity. It was a three-group experiment. Your three conditions were a control condition with no noise, a low-noise condition, a high-noise condition. Your three-treatment means are different. State the null hypothesis for your experiment.
6. a) Jelly is going to run an experiment tomorrow in which her significance level will be p < .05. What does it mean?
b) If she decides instead to use p < .01 as her significance level, will it be easier or harder for her to detect the effect of the independent variable? Why?
7. For each of the following examples explain whether the researcher has committed a Type 1 or Type 2 error and why.
a) Dr. A rejects the null hypothesis although the independent variable had no effect.
b) Dr. C rejects the null hypothesis when it falls.
c) Dr. E does not reject the null hypothesis even though the independent variable had an effect.
(Note: A type I error (false-positive) occurs if an investigator rejects a null hypothesis that is actually true in the population; a type II error (false-negative) occurs if the investigator fails to reject a null hypothesis that is actually false in the population.)

Added by Samuel D.

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