What type of variable is observed to assess the effect of a treatment?
dependent
a hat contains 100 marbles. 25 are blue, 30 are green, 10 are red, and 35 are yellow. If you randomly select a marble from the hat, what is the probability of selecting a blue marble?
p = 25/100 or 1/4
assume you have sampling with replacement. you have 10 dogs, each of a different breed and want to sample 3. what is the probability of selecting the second dog?
1/10
which of the following images depicts a reliable but not valid measure?
First image
explain a ratio level of measurement.
characterized by the presence of an absolute/meaningful zero
ex: number of correct answers on an exam
list the three measures of central tendency
mean, median, mode
what is the "good" kind of variability (the kind you can account for)
systematic
what functions as a measure of the standard or average distance population scores are from the mean?
standard deviation
what term is used to describe how peaked or flat a curve is?
kurtosis
what is the computational formula for calculating sums of squares?
what is the mean and standard deviation of a z-score distribution?
mean = 0
standard deviation = 1
what is the mean and standard deviation of a t-score distribution?
mean = 50
SD = 10
For a population with ? = 50 and ? = 10, what is the X value corresponding to z = 0.4?
X = 50 + 0.4(10)
= 50 + 4
= 54
You conduct an ANOVA (F test) and it is significant. What is your next step?
Conduct a post-hoc test to determine where the group differences are
-a significant ANOVA only tells you that at least one of the groups is different from the other. It doesn't tell you which one(s)
what is the difference between a statistic and a parameter?
a statistic is any measure obtained from a sample
a parameter is any measure obtained from a population
high bias and low variability?
high bias and high variability?
low bias and high variability?
low bias and low variability?
if you have an observed p value and alpha, when do you reject the null hypothesis?
when observed p < alpha
You have two samples (Group 1 and Group 2). Write out the null and research hypotheses using symbols and helpful notation for a non-directional hypothesis.
H0: �group1 = �group2
H1 : �group1 ? �group2
Describe a Type I error, including the symbol represents it.
the probability that you reject the null hypothesis when you should not have rejected it
symbol is:
type II error
the probability that you fail to reject the null hypothesis when you should have rejected it
symbol is:
If alpha is decreased, what does this do to the critical region?
Decreases the critical regions, making it harder to reject the null hypothesis.
What is the major difference between correlation and regression?
Correlation: CAN'T predict anything; only associations
Regression: CAN predict
r = -.14
Describe this relationship.
Weak, negative correlation
What does R2 tell you?
The proportion of variability in the outcome variable accounted for by the predictor(s).
Explain why you would choose running a multiple linear regression instead of several simple linear regressions if you have multiple predictors?
Multiple linear regression "subtracts out" the overlap between the predictor variables to determine each predictor's unique contribution to the variability in the outcome variable.