Unit 1
Likert scales are typically what level of precision?
Ordinal
What does a small standard deviation tell us?
The scores are generally close together (not too much variation in the results)
How do you create a sale average in jamovi? Walk me through the steps.
(1) run internal reliability (factor) to get Cronbach's alpha and see if any items need to be dropped/recoded, (2) create a new computed variable column, (3) take the average of the remaining/recoded items to get the scale average
What is an example of ratio data?
-amount of drug given to participants
-counting how many times a behavior happens
Shonda measures happiness in a sample of 20 Dominican students (scale of 1-10). She calculates a 95% confidence interval [5,8] for average happiness amongst all DU students. According to this confidence interval...
About 95% of studies conducted like hers capture the population mean for happiness in their CI.
In a research study, two groups of students were given a cognition test. Half the students were in a cold room, and half were in a neutral temperature room. The researcher grading the tests felt bad for the students in the cold room and graded them a little easier on their cognition test. Why is this a confound?
The groups were not graded evenly and therefore the results will be invalid.
How would we compare two scores that were on different scales? Example: one measure that is 1-7, and another that is 1-10.
Z-score to z-score method
What is the raw score regression equation? Where do you find it in Jamovi?
It is our prediction equation for predicting Y from X. It can be found underneath the r value in the correlations single group analysis in Jamovi (press extra details and regression to get this).
Will you have to do step-by-step calculations on the exam? What excel functions do you need to know?
No! =stdev.s, =average, =sum, =var.s, =pearson
What are the descriptive statistics you report?
M and CI, s, N, r and CI(if applicable)
Clinton is interested in how different study techniques improve learning. To do this research, he needs to measure student learning. Clinton has students read a chapter from a history textbook and then gives them a set of essay questions to measure how much they have learned from the chapter. He scores each essay question as a 0, 1, or 2 and then adds up the total. Clinton’s advisor, though, tells him that he needs to have another person also score the same essays, and that he should then compare the scores given.
What kind of validity/reliability does this address?
inter-rater reliability or inter-observer reliability
If I measured course grade and workshop attendance in a group of 20 students and found that r=-.80. Squaring this value (r2) would indicate what?
The strength of the relationship
A study was done to see the relationship between time in one's profession and income. If the predicted score is 102 thousand for 20 years in the same career, and a teacher studied still only makes 30 thousand dollars/year, what is the error in the prediction (the residual)?
72k
Study 1: Does caffeine make you smarter? To find out, Amanda gave an IQ test to 100 students. Prior to the test, half the students (determined randomly) were given a strong cup of coffee containing 100mg of caffeine; the other half was given a decaffeinated cup of coffee with 0mg of caffeine. She found that students given caffeine scored about 5 points higher than those who were not.
What is the independent variable in Study 1?
Exposure to caffeine
Create a scatterplot in excel (on one person's computer) with an old file from class. Include axis titles, chart title, regression line, and regression equation.
I'm going to come around and see what's up :)
Ella explains that for her study she has defined aggression as the number of hot peppers participants allocate to a fictitious competitor. This is her _____ definition of aggression.
Operational
How would we determine if there was a causal relationship?
Ex. Drinking more than 250mg of coffee causes one's hand to shake.
Randomly assign people to drink 0mg, 100mg, 250mg of coffee and then determine the level of hand shaking from participants.
If we find a relationship between subjective well-being and grit that is r=0.155 and say there is definitively a weak relationship between the two, what could we be missing?
-curvilinear scatterplot
-outliers
-restriction of range
-missing CI in this question)
How could you determine the test-retest reliability of a cognition measure?
Test cognition a second time with the same participants using the same measure for cognition.
What is the difference between the DV and the IV (dependent variable/independent variable)? What is an example of each?
DV is what is measured (construct), IV is what is manipulated (experimental variable).
Researchers asked patients taking Zoloft for one year at different dosages (25mg-200mg) if they felt a decrease in anxiety since taking their current dose. The measure for decrease in anxiety is at what level of precision?
Nominal
How do you know when something is the worst item on the scale?
The worst item will have a negative item-total correlation (if dropped, the alpha raises significantly).
What is the statistic that determines inter-item reliability, sometimes also called internal reliability?
Cronbach's alpha
What is probabilistic sampling?
Random sampling, using a population list and random assignment. It is trying to make the probability high that your sample will match the population.
Daphne conducts a study to determine the effectiveness of couple's counseling. Couples are randomly assigned to 0, 2, or 6 weeks of intensive counseling. After 6 weeks, all couples take a survey which asks about 4 different areas of relationship satisfaction: sexual compatibility, mutual respect, social support, and shared responsibility. How many levels does the IV (independent variable) have?
3