Psych Stat
What is the value of ΣX+1 for the scores 1, 6, 3?
11
What is the value of ΣX^2 for the scores 1, 0, 2, 4?
21
What is the value of (ΣX)^2 for the scores 1, 0, 2, 4?
49
In a grouped frequency distribution, one interval is listed as 50-59. Assuming that the scores are measuring a continuous variable, what are the real limits for this interval?
49.5-59.5
A population of N=8 scores has a sum of X=40. What is the population mean?
5
What is the value of (ΣX)^2 for the scores 1, 5, 2?
64
A sample of n=15 scores ranges from a high of X=11 to a low of X=3. If these scores are placed in a frequency distribution table, how many X values will be listed in the first column?
9
A researcher surveys a sample of n=200 college students and asks each person to identify his or her favorite movie from the past year. If the data were organized in a frequency distribution table, what would be listed in the first column?
A list of movies
A doctor data from his patients on whether or not they are a smoker to see how it impacts their health. In this example, whether or not someone is a smoker is
A quasi-independent variable
What is the first step to be performed when computing Σ(X+2)^2?
Add 2 points to each score
Which of the following is done last in the order of operations?
Addition
If it is impossible to divide the existing categories of a variable, then it is an example of a(n) _____ variable.
Discrete
If it is impossible to divide the existing categories of a variable, then it is an example of a(n) ______ variable.
Discrete
A discrete variables must be measured on a nominal or an ordinal scale.
False
A group of quiz scores ranges from 3 to 10, but no student had a score of X=5. If the scores are put in a frequency distribution table, X=5 would not be listed in the X column.
False
A recent report concluded that children with siblings have better social skills than children who grow up as an only child. This is an example of an experiment study.
False
Classifying people into two groups on the basis of gender is an example of measurement on an ordinal scale.
False
For the following distribution of scores, 20% of the individuals have scores of X=1. X: 5, 4, 3, 2, 1 f: 2, 8, 5, 3, 2
False
For the following distribution, 11 people have scores greater than X=14. X. f. 20-24 2 15-19 5 10-14 4 5-9 1
False
For the following scores, Σ X^2=49. Scores: 1, 4, 2, 0
False
If a set of exam scores forms a negatively skewed distribution, it suggests that the majority of the students did not score well on the exam.
False
In February in New York, the daily high temperatures are typically low with only a few relatively warm days. A frequency distribution showing the daily high temperatures would probably form a negatively skewed distribution.
False
To compute Σ X^2, you first add the scores, then square the total.
False
What kind of scale are most psychological variables assumed to follow?
Interval
After measuring two individuals, a researcher can say that Tom's score is 4 points higher than Bill's. The measurements must come from a(n) ______ scale.
Interval or ratio
Which of the following is true about the difference between interval and ratio scales
Interval scale may have a score of 0, but (unlike the ratio scales), but it does not represent the true absence of what is measured.
If a set of exams forms a negatively skewed distribution, what can you likely conclude about the students' scores?
Most of the students had relatively high scores
A population of scores has a mean of mean=22, median=23, and mode=26. What is the most likely shape for the population distribution?
Negatively skewed
Suppose a class takes a quiz and the majority of scores are high with fewer low scores. Which is the most likely shape of the distribution?
Negatively skewed
The students in a psychology class seemed to think that the midterm exam was very easy. If they are correct, what is the most likely shape for the distribution of exam scores?
Negatively skewed
Whether or not someone is in the experimental group of the control group in a study is what type of variable?
Nominal
Determining the class standing (1st, 2nd, and so on) for the graduating seniors at a high school would involve measurement on a(n) _____ scale of measurement?
Ordinal
Using letter grades (A, B, C, D, and F) to classify student performances on an exam is an example of measurement on a(n) ______ scale of measurement.
Ordinal
A researcher is curious about the average monthly cell phone bill for high school students in the state of Florida. If this average could be obtained, it would be an example of a ____.
Parameter
A group of researchers believed people's perceived economic status (high or low) would cause changes in their support for political policies that redistributed income. What was their independent (or quasi-independent) variable?
Perceived economic status
A researcher uses an anonymous survey to investigate the television-viewing habits of American adolescents. The entire group of American adolescents is an example of a _______.
Population
A population of scores has a mean of mean=26, median=23, and mode=22. What is the most likely shape for the population distribution?
Positively skewed
What kind if measurement scale is necessary to conclude that one score is twice as big as another?
Ratio
What scale of measurement is being used when a teacher measures the number of correct answers on a quiz for each student?
Ratio
A researcher uses an anonymous survey to investigate the television-viewing habits of American adolescents. Based on the set of 356 surveys that were completed and returned, the researcher finds that these students spend an average of 3.1 hours each day watching television. For this study, the set of 356 students who returned surveys is an example of a _________.
Sample
What kind of distribution shape can NOT be symmetrical?
Skewed
A researcher records the change in weight (gained or lost) during the first semester of college for each individual in a group of 25 freshman, then calculates the average change in weight. The average is an example of a _____.
Statistics
What is the final step to be performed when computing Σ(X-2)^2
Sum the squared values
What is the shape of the distribution for the following set of data? X. f 5. 5 4. 3 3. 1 2. 3 1. 5
Symmetrical
A researcher conducts an experiment to determine whether moderate doses of St. John's Wort have any effect on memory for college students. For this study, what is the independent variable?
The amount of St. John's Wort given to each participant
What of the following is an example of a continuous variable?
The amount of time to solve a problem
Which of the following is an example of a continuous variable?
The amount of time to solve a problem
What additional information is obtained by measuring two individuals on an ordinal scale compared to a nominal scale?
The direction of the difference
A recent study reports that students who just finished playing a prosocial video game were more likely to help others than students who had played a neutral or antisocial game. For this study, what is the independent variable?
The kind of game given to the students
If group 1 in your study has a standard deviation of 10 and group 2 has a standard deviation of 5, then you know that
The scores in group 1 are more spread out than the scores in group 2
A high school gym teacher records how much time each student requires to complete a one-mile run. This is an example of measuring a continuous variable.
True
A histogram is constructed so that adjacent bars touch.
True
A normal distribution is an example of a symmetrical distribution.
True
A recent report concluded that college graduates have higher life-satisfaction scores than individuals who do not receive college degrees. For this study, graduating versus not graduating is an example of a quasi-independent variable.
True
For the following scores, Σ(X+1) = 9 Scores: 1, 3, 0, 1
True
If a researcher measures two individuals on a nominal scale, it is impossible to determine which individual has the larger score.
True
If a researcher measures two individuals on an ordinal scale, it is impossible to determine how much difference exists between the two people.
True
In a frequency distribution is presented in a polygon, then the scores were measured on an interval or ratio scale.
True
In a positively skewed distribution, the scores pile up on the left side of the distribution and taper off to the right side.
True
Recording the number of text messages you receive each day would be an example of measuring a discrete variable.
True
The first step in computing Σ(X+1) is to add 1 point to each score.
True
When is the mode the only measurement of central tendency that can be used?
When the variable is nominal or categorical
When is a grouped frequency table most useful?
When there are many different scores on the dataset
In a frequency distribution graph, frequencies are presented on the ____, and the scores (categories) are listed on the _____.
Y axis; X axis
A researcher is interested in testing whether introverts or extraverts have better short-term memory. Introversion/Extraversion is....
a quasi-independent variable
An example of a variable measured on an ordinal scale is
college classification (freshman, sophomore, etc)
The type of treatment used in a research study describes the
independent variable
In an experiment, the independent variable is ______ by the experimenter
manipulated
An instructor examines the scores on her first exam, which has a typical scale of 1 to 100 and a fairly normal distribution. Which measure of central tendency is appropriate for this variable?
mean median mode **all of them
For a perfectly symmetrical normal distribution, which relationship is always true?
mean= median= mode
The measure of central tendency that is the same as the 50th percentile is the
median
An example of a variable measured on a ratio scale is
number of random acts of kindness observed
Which of the following is an example of a discrete variable?
number of stoplights in a city
In a distribution with positive skew, scores with the highest frequencies are _____.
on the left side of the distribution
A person's class rank amongst their high school class is an example of what type of variable
ordinal
Although a research study is typically conducted with a relatively small group of participants known as a _____, most researchers hope to generalize their results to a much larger group known as a ______.
sample; population
Dr. Spearmint conducts a study where he changes the room temperature and measures its effect on participants' performance on a simple task. What is his dependent variable?
task performance
For an experiment comparing two methods of teaching social skills training to autism children, the independent variable is _____ and the dependent variable is ____.
teaching methods; the social skills that are learned
Standard deviation is best conceptualized as
the average distance scores are from the mean
A standard deviation is conceptually most similar to what?
the average of all deviations
A veterinarian collects information about the weight of her clients' dog, cats, gerbils, and hamsters. For which group is the standard deviation for weight probably larger?
the dogs
In a frequency distribution graph, the vertical axis shows
the frequency
A set of students is surveyed about their major, what is the best measure of central tendency for this variable?
the mode
Why are unsquared deviation scores not useful measures of variability in a sample?
unsquared deviation scores across a sample will always add up to 0
When is the mean considered LEAST useful as a measure of central tendency?
when the distribution is very skewed or contains extreme outliers
Under what circumstances is the median likely to produce a better measure of central tendency that the mean?
with an extremely skewed distribution
You are instructed to subtract 4 points from each score and find the sum of the resulting values. How would this set of instructions be expressed in summation notation?
Σ(X-4)
You are instructed to subtract 4 points from each score, square the resulting value, and find the sum of the squared numbers. How would this set of instructions be expressed in summation notation?
Σ(X-4)^2
