5340 Stat Quiz Questions
In excel, to subtract 5 from 10 and multiply the difference by 7, you would use which of the following?
(10-5)*7
When the risk level is .01, the critical value for the z-score is ____.
2.58
If you want to calculate a z score, then besides the raw data, what other information must you have?
mean and standard deviation of the data
Which of the following statements is true?
measures of variability include range, standard deviation, and variance.
When the right tail of a distribution is shorter than the left tail, the distribution is said to be
negatively skewed.
In order to calculate the t value for independent samples, what information, besides the raw data, does the researcher need?
number of subjects, measn, and avariances of both groups
If the type I error is at the .05 level, which of the following is a correct statement?
p<.05
the term leptokurtic refers to a graphed distribution that is relatively
peaked
Which of the following has occurred when a researcher rejects the null hypothesis and it is in fact false?
power
To compute an biased standard deviation, you need
raw scores, the means and the total number of values.
In the standard deviation formula, X refers to the
raw sore
Which of the following is a true statement?
the standard error of the mean is the best estimate of the standard deviation of all the means of the population
If the test statistic z= 2.05 and the risk level is at .05,what must be true?
the value 2.05 is the obtained value
What percent of all scores fall above a z score of +1?
16%
When p = .21, what conclusion can be drawn?
the researcher can accept the null hypothesis
When you want to calculate the average score of two numbers using excel, which of the following is the correct formula?
(8+9)/2
In excel, what symbol is associated with the multiplication operation?
*
If the population mean is 10, the sample mean is 11, and the standard error of the mean is 1.5, what is the Z-test score?
.67
If the standard deviation of the population is 10 and the sample size is 144, what is the standard error of the mean?
.83
Calculate the unbiased standard deviation of 1, 2, 3 , and 4
1.29
When the risk level is .05, the critical value for the z-score is ____.
1.96
In excel, dividing 12 by 2 is accomplished with which of the following?
12/2
Under the normal curve, approximately what percent of scores fall between -1 and -2 standard deviations from the mean?
14%
Which of the following sets of data is the most variability?
15,10,2,2,1
What is the exclusive range of the following data set: 10, 20, 5, 8, 21
16
If the z score is 4, the raw score is 40, and the data set's standard deviation is 9, then what is the mean?
4
If the z score is 2, and the data set's standard deviation is 10 and mean is 20, then what is the raw score?
40
If a raw score is 50, and the data set mean is 5 and standard deviation is 9, then what is the z score?
5
If you have a set of data with a range of 3 to 58 and you want 11 intervals, what should the size of each interval be?
5
If you have a set of scores ranging from 150 to 250 ad want 20 intervals, what should class interval be?
5
The mean test score of Mr. Johnson's math class, with 30 students enrolled, was 80, and the standard deviation was 10. A total of 500 students in the school took the same math test, with an overall average of 75 and a standard deviation of 5. What is the z-score?
5.49
If the number of participants in Group 1 is 30 and the number in Group 2 is 28, what is the associated degrees of freedom for a t-test of independent samples?
56
Under the normal curve, approximately what percent of scores fall in the range of -1 to +1 standard deviations from the mean?
68%
What percent of all scores fall below a z score of +1?
84%
What Greek letter is associated with type II error?
BETA
When using excel to calculate unbiased standard deviation, which of the following should you use?
STDEV.S
When you want to add up a set of data using excel, which of the following should you use?
SUM
Which of the following is true?
Standard deviation is affected by extreme scores.
To compute the t value, the researcher must approximate the sample size by calculating which of the following?
degrees of freedom
Descriptive statistics are used to
describe and organize the characteristics of a collection of data.
In excel, to take 4 to the power of 2, you could use which symbol?
^(caret)
Which of the following statements is true?
a class interval is a range of numbers, a class interval could e 5, 10, or 20, an analyst typically starts the west class interval at 0.
A frequency polygon is
a continuous line that represents the frequencies of scores within a class interval, a line connecting the midpoint of each bar/column in a histogram
a set of mathematical operators that perform a particular mathematical task is called
a formula
Which of the following is true?
a function is predefined formula and a formula is a set of mathematical operators that perform a particular mathematical task.
A frequency distribution is
a method of tallying how often certain values occur and a method of representing how often certain values occur.
A function is
a predefined formula.
From 100 third graders at Jones Elementary School, 10 were selected to participate in a research study. These 10 third graders are
a sample.
When you describe the average age and the most common major of a group of students, what are you using?
descriptive statistics
What Greek letter is associated with Type I error?
alpha
Which of the following is an example of the way in which statistical significance is usually stated?
alpha=.05
In Excel, a dollar sign in a function indicates
an absolute reference to the cell
Which of the following characteristics is associated with the "tails" of the normal curve?
asymptotic behavior
When you want to calculate the average of a set of data using excel, which of these should you use?
average
What is the standard deviation?
average amount variability in a set of scores
Which of the following statements is NOT true?
both are true- according to the central limit theorem, when sample size increases, the sample's distribution approaches a normal distribution and according to the central limit theorem, the value associated with a large number of independent observations will have a normal distribution
When the significance level is at .01, which of the following is true?
confidence level is 99%
Which of the following occurs when a researcher accepts a null hypothesis that is in fact true?
correct decision
Which of the following statements is NOT true?
each participant is tested once in the t test for independent samples
the term platykurtic refers o a graphed distribution that is relatively
flat.
the term Kurt's is refers to graphed distribution's
flatness and peakedness
A good reason to use a one-sample Z-test is to determine whether the sample values are different from those of
given population
Mr. Johnson wants to determine whether the mean test score in his math class is the same as that of all the students in 12th grade. The mean score of his class, with 30 students enrolled, was 80, and the standard deviation was 10. A total of 500 12th graders in the school took the same math test, with an overall average of 75 and a standard deviation of 5. What conclusion should Mr. Johnson arrive at, using p = .05?
his math class's average differs form the 12th graders overall average
The tally
ho method is used to show the frequency of scores with each class by using tallies, and show how often certain scores occur relative to other scores.
to create a histogram in excel, you need to
identify the cells that contain all the data and identify bins
Which of the following statements is true?
in a positively skewed graph, the mean is greater than the median, in a negatively skewed graph, the mean is smaller than the median, data are less dispersed in a leptokurtic graph than in a platykurtic graph
________ are used to make inferences based on a smaller group of data
inferential statistics
Consider this statement: Males and females differ significantly in their movie preferences. Which of the following is true about this statement?
it is a nondirectional hypothesis
What is variability?
it reflects how scores differ from one another and variability includes range, standard deviation, and variance.
Consider this statement: Boys raise their hands significantly less in class than do girls. Which of the following is NOT correct about this statement?
it requires a two tailed test]
In the denominator of the standard deviation formula, n sub rated by 1 instead of n is used because
it results in a conservative estimate of the population value.
The skewness refers to a graphed distribution's
lack of symmetry.
If the obtained t value is 7.14 and the critical value is 6.10, the researcher should
reject the null hypothesis
In order to compute the z score for a one-sample Z-test, what values are needed?
sample mean, populationmean, and standard error of the mean
In the standard deviation formula, what does n represent?
sample size
When the obtained value is .15 and the critical value is 0.56, the researcher
should accept the null hypothesis
If the obtained value for a nondirectional test is -3.58 and the critical value is 2.36, the researcher
should reject the null hypothesis
When the obtained value of a test statistic is .78 and the critical value is .23, the researcher
should reject the null hypothesis
If you decide you are willing to take a .05 chance of incorrectly rejecting your null hypothesis, what is the term for this chance?
significance level
Which of the following is not true?
standard deviation is a less precise measure of variability than range.
Variance is the
standard deviation squared.
To use Excel's STANDARDIZE function to compute the standard score, the user should enter which of the following?
standardize (x, standard deviation)
A researcher is willing to take some risk of rejecting the null hypothesis when it is actually true. What is the term for this degree of risk?
statistical significance
If you fold a normal distribution graph on the center line of the curve, the two halves of the curve overlay each other. What is the term for this characteristic?
symmetry
To use Excel's T.TEST function, the user enters which of the following?
t test array 1 array 2 tails type
Which of the following statements is true?
t-test for independent samples tests only two groups
A histogram is a visual representation
that uses bars and that shows frequency distribution.
which of the following is true?
the larger the standard deviation, the larger the variability, the larger the standard deviation, the more spread out the data are, standard deviation is a measure of dispersion.
Which of the following is a characteristic of the normal curve?
the mean, median and mode are the same
If the obtained z value is lower than the critical value, then what must be true?
the null hypothesis can be accepted
In Excel, the function Z.TEST can be used to calculate the z-score. What does Z.TEST provide?
the probability that a score belongs to the population
If the test statistic z = 2.05 and the risk level is at .01, what must be true?
the probablity is equal to or less than 1% that on any one test of the null hypothesis the sample and the population averages will differ significantly
Which of the following statements is NOT true
the purpose of a research study is to prove a hypothesis
Which of the following is true of z scores that fall below the mean?
they are negative
Which of the following is an appropriate reason to use the t-test for independent samples?
to determine whether males and females hold different political views
What is the purpose of the one-sample z-test?
to examine the differnce between one dample and one population
Imagine that your null hypothesis is true, but you reject it. What has happened?
type 1 error
If a researcher accepts the null hypothesis when it is really false, what has occurred?
type 2 error
When calculating the standard error of the mean, the standard deviation of the population is represented by ____.
σ