Exam 1
A population has SS=100 and d2=4. What is the value of E(X-m) for the population?
0
Which set of scores has the smallest standard deviation?
145, 143, 145, 147
For a perfectly symmetrical distribution with a median of 30, what is the value of the mean?
30
A set of n=15 pairs of scores (X and Y values) has SSx=4, SSy=25, and SP=6. The Pearson correlation for these data is
6/10
For a population with m=100 and and standard deviation=20, what is the X value corresponding to z=-0.75?
85
If it is impossible to divide the existing categories of a variable, then it is an example of a(n) ________ variable.
Dependent
The scatter plot for a set of X and Y values shows the data points clustered in a nearly perfect circle. for these data, what is the most likely value for the Pearson correlation?
Either positive or negative near 0
True or False: A negative correlation means the decreases in the X variable tend to be accompanied by decreases in the Y variable
False
True or False: A positive deviation always indicates a score that is less than the mean
False
True or False: A researcher interested in vocabulary development obtains a sample of 3-year-olds to participate in a research study. The average score for the group of 20 is an example of a parameter
False
True or False: An experimental research study typically involves measuring two scores for each individual in one group of participants
False
True or False: Classifying people into two groups on the basis of gender is an example of measurement on an ordinal scale
False
True or False: For a negatively skewed distribution, the mean usually has a larger value than either the median or the mode
False
True or False: If the population variance is 5, then the population standard deviation is 25
False
True or False: In distribution with m=80 and stan. dev. =20, a score of X=95 corresponds to z=1.50
False
True or False: The mean is considered to be the balance point for distribution because exactly half of the scores are located above the mean and exactly half are below the mean
False
A researcher is measuring th amount of time needed to solve a set of anagrams for a sample of n=15 students. However one of the participants fails to solve the problems so the researcher has an undetermined score. What is the best measure of central tendency for these data?
Median
A distribution is positively skewed. Which is the most probable order, from smallest to largest, for the three measures of central tendency?
Mode, median, mean
True or False: If two individuals in the same population have identical X scores, they also will have identical z-scores
T
A researcher conducts an experiment to determine whether moderate doses of St. Johns Wort have any effect of memory for college students. For this study, what is the independent variable?
The amount of St. Johns Wort given to each participant
Which if the following is an example of a continuous variable?
The amount of time to solve a problem
True or False: A correlational study is used to examine the relationship between two variables but cannot determine whether it is a cause and effect relationship
True
True or False: A correlational study typically uses only one group of participants but measures two different variables (two scores) for each individual.
True
True or False: A researcher is interested in the average income for registered voters in the US. The entire group of registered voters is an example of a population.
True
True or False: For a distribution with one or two extreme scores, the median is usually a more representative value than the mean.
True
True or False: For a sample with a standard deviation of s = 10, a score with a deviation of +5 will have a z-score of z=0.50
True
True or False: For any distribution of scores, the location identified by z=+1 and the location identified by z=-1 are exactly the same distance from the mean
True
True or False: There are situations for which it is either impossible to compare a mean or the mean does not provide a central representation value
True
True or False: To determine how much difference there is between two individuals, you must use either an interval or a ratio scale of measurement
True
True or False: if you have a score of X=66 on an exam with m=70, you should expect a better grade if stan. dev. is 10 than if stan. dev is 5
True
On an exam with a score of m=70, you have a score of X=75. Which of the following values for the standard deviation would give you the highest position within the class?
d=10
The students in a psychology class seemed to think that the midterm was very easy. If they are correct, what is the most likely shape for the distribution of exam scores?
negatively skewed
For an experiment comparing two methods for teaching social skill training to autistic children, the independent variable is ______ and the dependent variable is _____.
teaching methods; the social skills that are learned
A recent study reports that elementary school students who were given a nutritious breakfast each morning had higher test scores than students who did not receive the breakfast. For this study, what is the independent variable?
whether or not a breakfast was given to the students