Stats Review

Identify the appropriate statistic

• A researcher randomly assigns five individuals to receive a new experimental procedure and five to a control condition. At the end of the study, all 10 are measured. Scores for those in the experimental group were 7, 6, 9, 7, and 6. Scores for those in the control group were 5, 2, 4, 3, and 6.

Identify the appropriate statistic

• A researcher randomly assigns five individuals to receive a new experimental procedure and five to a control condition. At the end of the study, all 10 are measured. Scores for those in the experimental group were 7, 6, 9, 7, and 6. Scores for those in the control group were 5, 2, 4, 3, and 6.– Independent measures t-test

Identify the appropriate statistic

• An experiment compares the effects of four treatments, giving each treatment to 20 participants and then assessing their performance on a standard measure.

Identify the appropriate statistic

• An experiment compares the effects of four treatments, giving each treatment to 20 participants and then assessing their performance on a standard measure.– One way ANOVA

Identify the appropriate statistic• A medical researcher has heard anecdotal evidence that certain anti-

depressive drugs can have the positive side-effect of lowering neurological pain in those individuals with chronic, neurological back pain, when administered in doses lower than those prescribed for depression. The researcher identifies 3 well-known, anti-depressive drugs which might have this positive side-effect, and labels them Drug A, Drug B and Drug C. The researcher then recruits a group of 60 individuals with a similar level of back pain and randomly assigns them to one of three groups - Drug A, Drug B or Drug C treatment groups - and prescribes the relevant drug for a 4 week period. At the end of the 4 week period, the researcher asks the participants to rate their back pain on a scale of 1 to 10, with 10 indicating the greatest level of pain. The researcher wishes to compare the levels of pain experienced by the different groups at the end of the drug treatment period.

Identify the appropriate statistic• A medical researcher has heard anecdotal evidence that certain anti-

depressive drugs can have the positive side-effect of lowering neurological pain in those individuals with chronic, neurological back pain, when administered in doses lower than those prescribed for depression. The researcher identifies 3 well-known, anti-depressive drugs which might have this positive side-effect, and labels them Drug A, Drug B and Drug C. The researcher then recruits a group of 60 individuals with a similar level of back pain and randomly assigns them to one of three groups - Drug A, Drug B or Drug C treatment groups - and prescribes the relevant drug for a 4 week period. At the end of the 4 week period, the researcher asks the participants to rate their back pain on a scale of 1 to 10, with 10 indicating the greatest level of pain. The researcher wishes to compare the levels of pain experienced by the different groups at the end of the drug treatment period. – Kruskal-Wallis test

Identify the appropriate statistic

• A researcher studied the relation between psychotherapists’ degree of empathy and their patients’ satisfaction with therapy

Identify the appropriate statistic

• A researcher studied the relation between psychotherapists’ degree of empathy and their patients’ satisfaction with therapy– Correlation

Identify the appropriate statistic• A researcher wants to examine whether music (“no

music", "classical music" and "dance music“) has an effect on the perceived psychological effort required to perform an exercise session. The researcher recruited 12 runners who each ran three times on a treadmill for 30 minutes. For consistency, the treadmill speed was the same for all three runs. In a random order, each subject ran: (a) listening to no music at all; (b) listening to classical music; and (c) listening to dance music. At the end of each run, subjects were asked to record how hard the running session felt on a scale of 1 to 10, with 1 being easy and 10 extremely hard

Identify the appropriate statistic• A researcher wants to examine whether music (“no music",

"classical music" and "dance music“) has an effect on the perceived psychological effort required to perform an exercise session. The researcher recruited 12 runners who each ran three times on a treadmill for 30 minutes. For consistency, the treadmill speed was the same for all three runs. In a random order, each subject ran: (a) listening to no music at all; (b) listening to classical music; and (c) listening to dance music. At the end of each run, subjects were asked to record how hard the running session felt on a scale of 1 to 10, with 1 being easy and 10 extremely hard – Friedman test

Identify the appropriate statistic

• A director of a small psychotherapy clinic is wondering whether there is any difference in the use of the clinic during different seasons o fthe year. Last year, there were 28 new clients in the winter, 33 in the spring, 16 in the summer, and 52 in the fall. On the basis of last year’s data, should the director conclude that seasons makes a difference?

Identify the appropriate statistic

• A director of a small psychotherapy clinic is wondering whether there is any difference in the use of the clinic during different seasons o fthe year. Last year, there were 28 new clients in the winter, 33 in the spring, 16 in the summer, and 52 in the fall. On the basis of last year’s data, should the director conclude that seasons makes a difference?– Chi-square goodness of fit

Identify the appropriate statistic• A pain researcher is interested in finding methods to

reduce lower back pain in individuals without having to use drugs. The researcher thinks that having acupuncture in the lower back might reduce back pain. To investigate this, the researcher recruits 25 participants to their study. At the beginning of the study, the researcher asks the participants to rate their back pain on a scale of 1 to 10, with 10 indicating the greatest level of pain. After 4 weeks of twice weekly acupuncture the participants are asked again to indicate their level of back pain on a scale of 1 to 10, with 10 indicating the greatest level of pain. The researcher wishes to understand whether the participants' pain levels changed after they had undergone the acupuncture

Identify the appropriate statistic• A pain researcher is interested in finding methods to reduce

lower back pain in individuals without having to use drugs. The researcher thinks that having acupuncture in the lower back might reduce back pain. To investigate this, the researcher recruits 25 participants to their study. At the beginning of the study, the researcher asks the participants to rate their back pain on a scale of 1 to 10, with 10 indicating the greatest level of pain. After 4 weeks of twice weekly acupuncture the participants are asked again to indicate their level of back pain on a scale of 1 to 10, with 10 indicating the greatest level of pain. The researcher wishes to understand whether the participants' pain levels changed after they had undergone the acupuncture – Wilcoxon signed-rank test

Identify the appropriate statistic

• Researchers mailed a survey to a random sample of physicians. Half were offered $1 if they would return the questionnaire this was the experimental group); the other half served as a control group. The point of the study was to see if even a small incentive would increase the return rate for physicians surveys

Identify the appropriate statistic

• Researchers mailed a survey to a random sample of physicians. Half were offered $1 if they would return the questionnaire this was the experimental group); the other half served as a control group. The point of the study was to see if even a small incentive would increase the return rate for physicians surveys– Chi-square tests of independence

Identify the appropriate statistic

• Van Prooijen and colleagues (2004) carried out a series of studies focusing on the effect of belongingness and being able to voice one’s opinion about a decision on a person’s satisfaction with the decision making process. The researchers measured procedural satisfaction by asking the students to rate how satisfied they were with the way they were treated by the other people on their team.

Identify the appropriate statistic

• Van Prooijen and colleagues (2004) carried out a series of studies focusing on the effect of belongingness and being able to voice one’s opinion about a decision on a person’s satisfaction with the decision making process. The researchers measured procedural satisfaction by asking the students to rate how satisfied they were with the way they were treated by the other people on their team.– Factorial ANOVA

Identify the appropriate statistic

• The effectiveness of advertising for two rival products (Brand X and Y) was carried out at a local shopping centre. Participants were shown ads for two brands of coffee, which they then rated on the overall likelihood of them buying the product (out of 10, with 10 being “definitely going to buy the product”). Half of the participants gave ratings for one of the products, the other half gave ratings for the other product

Identify the appropriate statistic

• The effectiveness of advertising for two rival products (Brand X and Y) was carried out at a local shopping centre. Participants were shown ads for two brands of coffee, which they then rated on the overall likelihood of them buying the product (out of 10, with 10 being “definitely going to buy the product”). Half of the participants gave ratings for one of the products, the other half gave ratings for the other product– Mann-Whitney test

Some humour

http://www.youtube.com/watch?v=JS9GmU5hr5w