More exercises (1)

Info for questions 1-2. A researcher wants to examine whether bilinguals have an attentional advantage over monolinguals, and whether that effect is modulated by gender (male, female). The researcher selects 40 monolinguals (20 men and 20 women) and 40 bilinguals (20 men and 20 women). The average age of the sample was 68 years in both groups, with a range (amplitude) between 65 and 71 years. All participants had to perform a task that consisted of detecting small boxes in a computer screen. Reaction time and accuracy were collected.

Question 1:

a) Which are the independent and dependent variables?

b) Is this an experiment or a quasi-experiment? Explain your answer

Question 2

a) If we want to organize the data to compute statistics with, say, SPSS, how many rows and columns are necessary? (and why)

b) Let’s imagine that the reaction times of bilinguals were substantially shorter than those of monolinguals, regardless of gender. What would be your conclusions? What follow-up experiment can you conduct?

Info for questions 3-4. We have a database (http://www.uv.es/mperea/neur.sav) that contains data from a sample of people: gender, age, 3 questions on anxiety (one reverse), level of introversion, and if they had to take an exam the following days or not.

Question 3

Generate the following variable (“overall anxiety level”) by adding the level of anxiety in the three questions ---take into account that the second question was inverse. Are there any differences in the level of anxiety depending on whether they will do an exam the next day or not? Look at the box and whisker diagram (you may also use the appropriate statistics). Justify briefly your conclusions. (Copy / paste the SPSS output as well.)

Question 4

Create two levels in the variable “age_dychotomized” (younger than 36 =1 “young adults”; 36 or older =2 “adults”) Are there any differences in the level of introversion in the two groups of age? Look at the box and whisker diagram (you may also use the appropriate statistics). Justify briefly your conclusions. (Copy / paste the SPSS output as well.) Do you think the average is a good index of central tendency for "introversion"? Or would it be preferable to some other index? If so, which one. Justify your answer.

More exercises (2)

Info for questions 1-2. A researcher wants to know the effectiveness of mindfulness against stress. We had 100 individuals in the study (50 men and 50 women), all of them with greater than 80th percentile on a stress score before the experiment. At random, 50 of them (25 men and 25 women) received mindfulness therapy for 8 weeks, and other people received a classic cognitive therapy also for 8 weeks. We measured the stress level of each individual before starting treatment, immediately after treatment, and 3 months after treatment.

Question 1:

a) Which are the independent and dependent variables?

b) Is this an experiment or a quasi-experiment? Explain your answer

Question 2

a) If we want to organize the data to compute statistics with, say, SPSS, how many rows and columns are necessary? (and why)

b) Let’s imagine that the arithmetic mean of stress in the group of mindfulness were 14.1 (before treatment), 6.7 (just after treatment) and 13.8 (3 months after treatment); in the cognitive therapy group, the corresponding means were 13.9 (before treatment), 9.8 (just after treatment) and 9.9 (3 months after treatment). Descriptively, what conclusions could you draw? Do you have any ideas for a follow-up study on the basis of these data? (i.e., which aspects of the design would you modify?)

Info for questions 3-4. We have a database that contains data from a sample of people: gender, age, 3questions on anxiety (one reverse), level of introversion, and if they had to take an exam the following days or not.

Question 3

Select those individuals with an age below 50. Are there differences in introversion between men and women? Look at the box and whisker diagram (you may also use the appropriate statistics). Justify briefly your conclusions. (Copy / paste the SPSS output as well.)

Question 4

Generate the variable "overall anxiety level" as the sum of the level of anxiety of the three questions on anxiety (keep in mind that the second question was inverse...). We want to know what is the score that leaves below it 95% of the data "overall anxiety level"—these people are possibly too high in anxiety and they may require psychological and/or medical attention. Copy / Paste from SPSS and justify your answer.