Practice 1. Statistics. (November 2015)

A researcher wants to examine whether the response times in an experiment are faster in the presence of another person during an experiment. The experiment consists of two blocks. 40 students took part in the experiment. In the first block, the participant performed a cognitive task alone—the experimenter measured the overall time in this initial block. In the second block, the participant performed a similar cognitive task with the difference that there was another person in the room (this other person, the "confederate" was actually brought by the investigator), and again, the experiment measured the overall time in the block

Question 1:

a) Which are the independent and dependent variables?

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

Question 2:

a) Is this an experiment or a correlational study? Explain your answer

b) Let’s assume that participants were faster in the presence of "confederate" than alone, and that the researcher concluded that the response times in cognitive tasks (or at least the cognitive task used in the study) are faster in the presence of another person. This has an obvious shortcoming: It could be argued that people are faster in the second block not necessarily by the presence of the other person (the "Confederate") but simply because they have more practice on the task. How would you modify the study to examine properly whether the presence of another person affects the participants’ response times?

Question 3:

We have a database with demographic variables and with variables related to well-being, optimism, pessimism, among others. It is available at the following link http://www.uv.es/mperea/bienestar.sav

Are there differences between men and women in the variable "well-being"? Create firstly the variable "well_being" by adding the 4 questions—before doing that, pay attention to the fact that the third item was reversed. (Each item goes from 1 to 6.) Just examine the box and whisker diagram, with the focus on central tendency and variability, in particular.

Question 4.

Indicate which one is the most common (i.e., most repeated) for the women in the sample.

Practice 2. Statistics (November 2015)

A researcher wants to examine whether the amount of tip given to waiters in a restaurant is influenced by the gender of the waiter (male, female) and by the fact of adding getting the check. There were 60 tables in the restaurant. Among these 60 tables, the first 30 tables in the evening (i.e., the customers who arrived somewhat early) will be given the check with candies (in half the cases, it was a waiter, and the other half it was a waitress), and the remaining 30 tables receive the check without the candy (in half the cases, it was a waiter, and the other half it was a waitress). The researcher measured the tip in each of the 60 tables.

Question 1:

a) Which are the independent and dependent variables?

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

Question 2:

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

b) How would you modify the study to reach more definitive conclusions? (e.g., can you improve the way the experiment was designed? How?)

Question 3:

Are there differences in the variable Well-Being depending on “situación personal” (personal situation) (single, married…). Create firstly the variable "well_being" by adding the 4 questions—before doing that, pay attention to the fact that the third item was reversed. (Each item goes from 1 to 6.) Just examine the box and whisker diagram, with the focus on central tendency and variability, in particular.

Question 4.

Which graph would you use for the variable “pessimism” for those individuals born in Spain in the sample. Why? Copy and paste from SPSS.

Practice 3. Statistics (November 2015)

A researcher wants to examine the effectiveness of a new therapy for treating agoraphobia (ie the phobia of open spaces) relatie to the standard therapy and whether its effectiveness differs between severe and mild cases. The simple was composed of 40 individuals diagnosed with agoraphobia (half "mild", half "severe"). Assignment to each therapy was at random, while keeping constant the ratio of mild vs severe cases (i.e., 10 mild, 10 severe in each treatment). Each session lasted 3 hours in each treatments, with a total of 10 sessions. The researcher measured the agoraphobia level just after the treatment, and also two months after treatment.

Question 1:

a) Which are the independent and dependent variables?

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

Question 2:

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

b) Would it have been desirable to have manipulated the psychological treatment in a within-subject design?

Question 3:

Let’s suppose that when creating the database, the score of prosperity for each person was be a point lower than it should be. Please fix it and create the variable "prosperity_ok". Once this is done, are there differences between men and women in the variable "prosperity_ok"? Just look at the box and whisker diagram (on the central tendency and variability, in particular)

Question 4.

In the case of those individuals born in Spain, please indicate a graph for the variable "gender" and discuss it briefly.

Practice 4. Statistics (November 2015)

A researcher wants to examine the effects of negative feedback (information on how the task was done but only in cases of error) in children and adults. The sample was composed of 20 children and 20 adults. Half of them, chosen at random (10 children, 10 adults) completed a series of trials without any feedback. The other half received negative feedback (ie, an ERROR after an error). The researcher measured the overall time to complete the tasks and also the subjective mood (after the task.

Question 1:

a) Which are the independent and dependent variables?

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

Question 2:

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

b) Let’s assume that the subjective mood after the test was substantially lower in the individuals with negative feedback than in the “no feedback” group. Logically, this limits the use of negative feedback as an element to learn. How would you improve the design of this study?

Question 3.

Which one is the score of "Pessimism" (more score, more pessimism) leaving below 85% of the individuals? (keep in mind that these individuals may need some help)

Question 4.

Exclude all individuals with 30 or more years (i.e., the idea is to have a sample of young people). Are there any differences between men and women in the variable "satisfaction" (satisfaction with life)? Just look at the box and whisker diagram (on the central tendency and variability, in particular)