Formative 1.5

Researchers have found a negative correlation between income and dental problems. What conclusion can correctly be drawn from this statement?

As income increases, the likelihood of dental problems decreases.

Using the data in sets A and B, which of the following statements is true?

Set B has a smaller standard deviation than set A.

2, 11, 2, 3, 3, 4, 2, 5 What is the mode of the number set above?

2

A group of psychologists wanted to develop an intelligence test that would be quicker to administer than the one they were using, which was a standardized test that required answering as many questions correctly as possible in a given time. The existing test was considered valid and reliable. In the psychologists' new test, participants had to find an image hidden in a visual display as quickly as possible. The psychologists collected data to determine the relation between the number of items the participants answered correctly on the original standardized test and the time it took them to spot the hidden image on the new test. The graph below displays the results. Which of the following values best represents the value of the statistic associated with the graph?

0.0

A psychologist administered the most recent edition of the Stanford-Binet IQ test to 50 students and their scores are shown in the chart above. How many students earned scores higher than two standard deviations above the mean?

2

−3, 3, 0, 3, −3 What is the standard deviation of the numbers above?

3

In data set B, the range is

4

12, 3, 3, 4, 8 What is the mean of the set of numbers above?

6

Which of the following is a statistical approach concerned with forming conclusions about the effect of the independent variable on variations in the dependent variable?

Inferential

Which of the following have been shown to have a positive correlation?

Perceived lack of control and learned helplessness

While reviewing scores from a chapter test, a teacher discovered that the mean score was higher than the median. Which of the following statements is most likely correct?

The distribution of scores for the test is positively skewed.

Which of the following is a valid conclusion that the researchers could have drawn from the data?

The new test produces scores that are generally unrelated to those produced by the original test.

A group of psychologists wanted to develop an intelligence test that would be quicker to administer than the one they were using, which was a standardized test that required answering as many questions correctly as possible in a given time. The existing test was considered valid and reliable. In the psychologists' new test, participants had to find an image hidden in a visual display as quickly as possible. The psychologists collected data to determine the relation between the number of items the participants answered correctly on the original standardized test and the time it took them to spot the hidden image on the new test. The graph below displays the results. Based on the graph, which of the following would most likely be used to assess the relation between the participants' scores on the two tests?

a correlation

A professor conducts a survey examining the relationship between pessimism and mental-health problems, and the results of her study are depicted in the scatterplot above. Which of the following types of relationship between pessimism and mental-health problems do her data suggest?

a positive correlation

A research group conducted a study investigating the connection between self-reported number of hours slept in a given week and scores on a happiness measure. Based on the scatterplot above, the group can report that there is

a positive correlation

The mean will be higher than the median in any distribution that

is positively skewed

In a normal distribution, which of the following statements is true about the area that falls between one standard deviation above and one standard deviation below the mean?

it contains the middle 68% of the distribution

Which of the following measures can be precisely located on the graph of a skewed distribution without doing any calculations?

mode

A teacher finds the distribution of scores on a final exam to be positively skewed with low variability. On the basis of this information, the teacher would be most justified in concluding that

the exam was too difficult

A test with normally distributed results was returned to a class of 100 students. Later, the teacher realized an error was made and added 10 points to each student's score. Which of the following must have changed as a result of the increase in scores?

the mode

Which of the following is an example of a strong negative correlation?

thinnest line

Which of the following scatterplots shows the strongest relation?

thinnest line

In data set A, the mean is

11

3 4 5 5 7 7 7 8 8 10 Ten participants in a treatment group were asked to rate their feelings of self worth on a scale of one to ten, with a value of ten indicating a very positive feeling of self-worth. The data for the participants are above. What is the mean for these data?

6.4

3 4 5 5 7 7 7 8 8 10 Ten participants in a treatment group were asked to rate their feelings of self worth on a scale of one to ten, with a value of ten indicating a very positive feeling of self-worth. The data for the participants are above. What is the mode for these data?

7

Which of the following is true of the frequency distributions shown in the graphs above?

Distribution B has more variation than distributions A or C.

A test has a mean of 80 with a standard deviation of 4. Which of the following scores is within one standard deviation of the mean?

77