besc-2
Which of these measures of central tendency works for nominal variables?
Neither the mean nor the median works for nominal variables.
Imagine a sample with n = 49 and a mean of 60 that comes from a population with a standard deviation of 7. Based on these data, what would be the 99.9% confidence interval for the population mean? (Use z-score of ±±3.29 for the 99.9% confidence level.)
(56.71, 63.29)
If a distribution has a mean of 20, then what is the deviation value for a score of 23?
+3
What is the z-score for a sample with n = 100 and M = 103 if the population parameters are 𝜇μ=100 and 𝜎σ=10?
+3
Which level of alpha for a hypothesis test has the lowest risk of a Type I error?
.01
For a normal distribution, kurtosis is...
0
If a distribution of 144 scores with a mean of 52 and a standard deviation of 12 is standardized, then the new distribution's mean will be _____.
0
What is the population variance for the following data? 4, 5, 5, 6
0.5
What is the sample standard deviation for the following data? 2, 2, 3, 4, 4
1
If the mean of a sample is 5 and the standard deviation is 2, then what is the z-score for a raw score of 8?
1.5
What is the point estimate for the population mean if the population standard deviation is 24, the sample size is 36, and the sample mean is 110?
110
What is the mode for the following data set? 1 2 2 2 2 2 3 3 3 3 4 4 4 5 5 5 5 6 6 7 7+
2
What is the IQR for this data set? 6, 4, 6, 6, 1, 6, 3, 4
2.5
What is the standard error for a distribution with 𝜎σ= 40 when n = 4?
20
If a person has a z-score of +2, what would their raw score be in a distribution with a mean of 20 and a standard deviation of 3?
26
What is the frequency of 4 in the following data set: 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 5
3
What is the mean for these data? 3, 1, 2, 5, 3, 4
3
If a distribution has a mean of 50 and a standard deviation of 5, then a raw score of 68 would have a z-score of...
3.6
What percent of the normal distribution is between z = -1 and z = 0?
34%
What is the median for the following data set? 1 2 2 2 2 2 3 3 3 3 4 4 4 5 5 5 5 6 6 7 7+
4
What is the range for this data set? 5, 1, 2, 6, 5
5
What percent of the normal distribution is within one standard deviation of the mean (i.e., |z| < 1)?
68%
If a person got a z-score of -2 on a test that had a mean of 80 and a standard deviation of 5, then what was their raw score?
70
What percent of a normal distribution is below a z-score of +1?
84%
Which is more precise (in the statistical sense): a point estimate or a confidence interval?
A point estimate
Which of the following distributions is leptokurtic?
B
For which levels of measurement can you calculate the mode?
Both ordinal and interval
If a sample's mean really is different from the comparison population's mean, then what is the easiest way to make sure that the null hypothesis would be rejected?
Getting as large a sample as possible
Which measure of variation is LEAST sensitive to outliers?
IQR
How is a confidence interval affected when the sample standard deviation decreases?
It becomes narrower
How is the point estimate affected when the sample standard deviation increases?
It does not change
When a distribution of raw scores is converted to z-scores, the mean and standard deviation of the distribution will be...
M=0, SD=1
A frequency bar graph would be most appropriate for which measurement scales?
Nominal or ordinal
Imagine two studies that are identical in every respect except the size of their samples. Sample A has an effect size of d = .40 and p-value of .001. Sample B also has an effect size of d = .40 but a p-value of .10. Which sample likely had the larger sample size?
Sample A
Imagine that samples - Sample A with n = 20 and Sample B with n = 200 - are drawn from the same population and confidence intervals are computed for the same variables, which sample will likely have the more precise confidence interval?
Sample B
What does the symbol 𝜇𝑋⎯⎯⎯⎯⎯μX¯ refer to?
The mean of the sampling distribution of means
The standard error of a sampling distribution is a function of two things:
The population standard deviation and the sample size
What does the symbol 𝜎2 stand for?
The population variance
What is the relationship between the standard deviation and the variance?
The standard deviation is the square root of the variance
If a person's blood sample tests positive for a disease when, in fact, the person does not have the disease, then...
a Type I error has occurred.
The normal distribution is _____.
a bell curve
The sample mean is ________ and a confidence interval for the mean is _______.
a descriptive statistic; an inferential statistic
A Type I error is also called...
a false positive
In a positively skewed distribution, the extreme scores are _____.
at the high end
Which type of chart would be most appropriate for a nominal variable?
bar graph
When the range of confidence for a confidence interval becomes lower - from 90% to 80%, for example - then the confidence interval will...
become narrower
This distribution can be described as _____.
bimodal
What is the range for this data set? 5, 3, 7+, 1, 4
cannot be calculated
One good use of the range is to...
check for outliers
The variable that is measured as the outcome in an experiment is called the _____ variable.
dependent
A bimodal distribution _____.
generally consists of two distinct populations
a chart of this type is called a...
histogram
In an experiment, the variable that the researcher manipulates is called the _____ variable.
independent
"Estimation" refers to a class of...
inferential statistics.
What is the minimum level of measurement needed to calculate the mean?
interval
The standard normal distribution...
is a bell curve with M = 0 and SD = 1.
A uniform distribution...
is platykurtic.
When calculating an effect size for the z-test...
it is most common to use Cohen's d.
in order to compute a one-sample z-test you must...
know the population standard deviation.
A narrow distribution that is sharply pointed in the middle and that has many outliers is also called _____.
leptokurtic
Which of the following is a defining characteristic of experiments?
manipulation
If a distribution of raw scores has a strong positive skew, then, given a sufficiently large n, the mean of the sampling distribution will be equal to the _____ of the raw score distribution.
mean
In a positively skewed distribution, which measure will generally have the highest value?
mean
Which measure of central tendency is MOST influenced by outliers?
mean
The three most common measures of central tendency are:
mean, median, mode
Which measure of central tendency is most appropriate for skewed distributions?
median
Which of these measures is LEAST affected by outliers?
median
The normal distribution is
mesokurtic
The distribution of all possible sample variances - if n is sufficiently large (e.g., n > 30) - will be...
mesokurtic.
In a negatively skewed distribution, which measure will generally have the highest value?
mode
What is the degrees of freedom for the sample variance?
n-1
As the size of samples in a sampling distribution increases (i.e., as n get bigger), then that distribution becomes...
narrower
Compared to a mesokurtic distribution, the peak of a leptokurtic distribution is...
narrower and higher.
A normal distribution has a value of skewness that is _____.
near zero
A variable that classifies people into racial or ethnic groups is what level of measurement?
nominal
If a person's sex is coded as Male = 0 or Female = 1, then that variable is at the _____ level of measurement.
nominal
If a person's sex is recorded as "Male" or "Female," then that variable is at the _____ level of measurement.
nominal
The only level of measurement that does not place scores or categories into order (and is therefore the lowest level of measurement) is the _____ level of measurement.
nominal
What is the minimum level of measurement needed to calculate the mode?
nominal
If a person has a z-score of 1 on a test, then their score is...
one standard deviation above the mean
What is the minimum level of measurement needed to calculate the median?
ordinal
In this boxplot, the circles on the right side of the box indicate _____.
outliers
When a distribution is relatively flat on the top and cuts off sharply at the ends with very few outliers, it is referred to as ____.
platykurtic
The larger group of people from which you got your observed group and to whom you wish to generalize your results is called the _____.
population
A distribution such as income that has most of the people at the bottom or middle but a few people with extremely high scores, is referred to as
positively skewed
This distribution is...
positively skewed
A histogram is appropriate when the data are _____
quantitative
The amount of time that a person spends on social media each week in minutes is a(n) _____ variable.
ratio
The highest level of measurement (i.e., the one that contains the most information) is the _____ level of measurement.
ratio
The number of students enrolled at UVU each year is an example of which level of measurement?
ratio
Which level of measurement has a true zero point?
ratio
When a distribution of raw scores is converted to z-scores, the shape of the distributions...
remains the same
If a researcher is using an critical value of ±±1.96 for a z-test and gets an observed z (i.e., test value) of +0.55 for a sample of n = 40, then the researcher should...
retain the null hypothesis
The group of people from whom you actually gather data is called the _____.
sample
Which measure requires a degrees of freedom calculation?
sample variance
What are the values of skewness and kurtosis for a normal distribution?
skewness = 0 and kurtosis = 0
As the mean for a distribution increases, then the width of the corresponding confidence interval will...
stay the same
In an experiment that looks at the effect of different teaching methods on student learning, the independent variable is...
teaching method.
One visual difference between a bar chart and a histogram is that in a histogram...
the adjacent bars touch but in a bar chart they are separate.
In a positively skewed distribution, which measure of central tendency has the highest value?
the mean
Which measure of central tendency is alwaysinfluenced by outliers?
the mean
Which of these measures is MOST affected by outliers?
the mean
Which of the following measures of central tendency can be used with data on the ratio level of measurement?
the mean or the mode
If a researcher is using alpha = .01 and gets a p-value for the z-test of p = .005, then...
the researcher should conclude that the results are unlikely to occur by chance if the null hypothesis is true.
The distribution of all possible sample variances (of a given sample size) is called...
the sampling distribution of variances.
If the formula for the population standard deviation were used with sample data, then result would be...
too small
According to the Central Limit Theorem, if a research takes sufficiently large samples (e.g., n > 30) from a bimodal distribution, then the resulting sampling distribution will be...
unimodal
If a researcher used a one-sample z-test to determine whether an experimental group was different from a general population, what she would actually be testing is...
whether their means are different.
If scores in a data set are very different from each other, then the standard deviation...
will be high
