stats final exam
Imagine a sample with n = 64 and a mean of 121 that comes from a population with a standard deviation of 16. Based on these data, what would be the 80% confidence interval for the population mean? (Use z-scores of ±1.28 for the 80% confidence level.)
(118.44, 123.56)
Imagine a sample with n = 49 and a mean of 183 that comes from a population with a standard deviation of 21. Based on these data, what would be the 99.9% confidence interval for the population mean? (Use z-scores of ±3.29 for the 99.9% confidence level.)
(173.13, 192.87)
Imagine a sample with n = 25 and a mean of 55 that comes from a population with a standard deviation of 10. Based on these data, what would be the 95% confidence interval for the population mean? (Use z-scores of ±1.96 for the 95% confidence level.)
(51.08, 58.92)
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)
Imagine a sample with n = 400 and a mean of 68 that comes from a population with a standard deviation of 20. Based on these data, what would be the 90% confidence interval for the population mean? (Use z-scores of ±1.64 for the 90% confidence level.)
(66.36, 69.64)
For a distribution with M = 100 and SD = 15, what is the z-score for a raw score of 112?
+0.8
What is the z-score for a sample with n = 100 and M = 103 if the population parameters are u=100 and o=10?
+3
Which of the following is an impossible value for R2 ?
-.01
If X and Y in a regression equation are both expressed as z scores - zX and zY - and the correlation between the two variables is r = .3, then what is the predicted value of zY when zX = - 1.2?
-0.36
Which z-score is closest to the mean of its distribution?
-0.9
If a population has a mean of 60 and a standard deviation of 15, what is the z-score for a sample of 9 people with an average of 55?
-1
In a data set with a mean of 50 and a standard deviation of 10, what z-score would a raw score of 35 have?
-1.5
If a distribution has a mean of 30 and a standard deviation of 3, then what is the z-score for a sample of 4 scores with a mean of 27?
-2
In a normal distribution, it is very unusual to find scores outside of what range of z-scores?
-3 and +3
In most distributions, nearly all (more than 99%) of the sample scores will be within what range of z-scores?
-3 to +3
What is the predicted value of Y when X = 20 using this regression equation? Y = 12 - 0.8*X
-4
Which of the following is an impossible value for both p and alpha?
.00
Which level of alpha for a hypothesis test has the lowest risk of a Type I error?
.01
When choosing a level of alpha for a hypothesis test, unless you have a compelling reason to do otherwise, you should use...
.05
If the mean of a sample is 4, and the standard deviation is 4, what is the z-score for a raw score of 6?
.5
A researcher calculating a Pearson's r found that there was no relationship between X and Y. The effect size for the data is .20
0
For a normal distribution, kurtosis is...
0
If a data set is converted to z-scores, the new mean of the data set 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
In a bimodal distribution with a mean of 80 and standard deviation of 20, what would the z-score be for a raw score of 80?
0
In a unimodal distribution with a mean of 80 and standard deviation of 20, what would the z-score be for a raw score of 80?
0
No matter what the shape of a distribution, if it is converted to z-scores, then its mean will be...
0
What is the value of kurtosis for a normal distribution?
0
What is the value of skewness for a normal distribution?
0
If X and Y in a regression equation are both expressed as z scores - zx and zy - and the correlation between the two variables is r = -.2, then what is the predicted value of zy when zx = - 0.5?
0.1
What is the population variance for the following data? 4, 5, 5, 6
0.5
If a data set is converted to z-scores, the new standard deviation of the data set is:
1
If a distribution has a mean of 100 and a standard deviation of 15, then what is the standard error for a sample of 225 scores?
1
No matter what the shape of a distribution, if it is converted to z-scores, then its standard deviation will be...
1
What is the interquartile range (IQR) for the these data: 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 4+
1
What is the sample standard deviation for the following data? 2, 2, 3, 4, 4
1
Which of the following is an impossible value for R2?
1.10
Which of the following is an impossible value for r2?
1.10
What is the standard deviation of the sample represented by the numbers below? 4 5 4 4 3 5 6 3 4 2 (Note that if you compare this question to the paper version of the practice final or the video reviews, one of the answers is slightly different. The correct one is listed here.)
1.15
What is the variance of the sample represented by the numbers below? 4 5 4 4 3 5 6 3 4 2 (Note that if you compare this question to the paper version of the practice final or the video reviews, one of the answers is slightly different. The correct one is listed here.)
1.33
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
If the population mean for a distribution is 150 and the standard deviation is 20, then what is the z-score for a sample of 100 people with an average score of 153?
1.5
What is the sample standard deviation for this data set? 3, 4, 2, 4, 7
1.87
Which z-score is furthest from the mean of its distribution?
1.9
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 predicted value of Y when X = 10 using this regression equation? Y = 30 - 1.2*X
18
What is the median for these data? 5, 1, 1, 3, 2
2
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 median for these data? 3, 1, 2, 5+, 2, 4
2.5
What is the standard error for a distribution with o= 40 when n = 4?
20
What is the predicted value of Y when X = 120 using this regression equation? Y = -350 + 5*X
250
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
If a population has a mean of 40 and a standard deviation of 8, what would the z-score be for a sample of 16 people with a mean of 46?
3
If a test has a population mean of 70 and standard deviation of 6, then what is the z-score for a sample of n = 9 scores with a mean of 76?
3
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 frequency of 2 in the following data set: 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 5
4
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 standard error of a distribution if ø= 20 and n = 25?
4
Which is the mode of the numbers below? 4 5 4 4 3 5 6 3 4 2
4
Which option is the mean of the numbers below? 4 5 4 4 3 5 6 3 4 2
4
Which option is the median of the numbers below? 4 5 4 4 3 5 6 3 4 2
4
What is the population variance for this data set? 4, 1, 6, 1
4.5
What is the range for the following dataset: 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 3, 3, 4, 5
5
What is the range for this data set? 5, 1, 2, 6, 5
5
If a raw score distribution has a mean of 12 and a standard deviation of 3, what number would have a z-score of -2?
6
What percent of the normal distribution has |z| < 1 (i.e., an absolute value less than 1)?
68%
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
For a distribution with M = 80 and SD = 6, what is the X score for a person who has a z-score of -1.5?
71
If the mean of X is 42, the mean of Y = 72, and rxy= 0, then what is the predicted value of Y when X = 30?
72
What is the point estimate for the population mean if the population standard deviation is 10, the sample size is 100, and the sample mean is 80?
80
What percent of a normal distribution is below a z-score of +1?
84%
In a normal distribution, what percent of the distribution is within between z = -3 and z = +3?
99.7%
A sampling distribution of means is:
A distribution of means from many samples
When the mean of the population that a sample comes from does not differ from the general population but the sample mean is nonetheless significantly different from the general population, then...
A type one error
A post-hoc test is required when the null hypothesis has been rejected for which statistical test?
ANOVA
The null hypothesis for an ANOVA is
All group means are statistically equal.
Which effect size is most appropriate for z-tests?
Cohen's d
What is the null hypothesis for the chi-squared test for independence? Group of answer choices
Each group on the predictor variable (or IV) will have identical proportions in each category of the outcome variable (or DV)
p-values are:
Influenced by sample size
How is a confidence interval affected when the sample standard deviation decreases?
It becomes narrower
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.
Committing a Type II error is defined as:
Not rejecting (i.e., Retaining) the null hypothesis when it should have been rejected
A data set has a non-linear relationship between two variables. Which of the calculations below are affected by this problem?
Pearson's r
Which of the following is true about regression towards the mean?
Predicted Y values will have less variation than actual observed values of Y Predicted Y values will not always be perfect unless r = +/- 1 Predicted Y values tend to be closer to the mean of Y than the observed values of X are to the mean of X
Which statistic is defined as the proportion of variance accounted in the dependent variable by the independent variable?
R-squared
Imagine two studies that are identical in every respect except the size of their samples. Sample A has an effect size of d = .20 and a p-value of .03. Sample B has an effect size of d = .20 and a p-value of .005. Which sample likely had the smaller sample size?
Sample A
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 two studies that are identical in every respect except their effect sizes. Sample A has a sample size of n = 80 and a p-value of .01. Sample B has a sample size of n = 80 and a p-value of .10. Which sample likely had the larger effect 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
Imagine that two 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 have the narrower confidence interval?
Sample B
A researcher conducts two studies on depression severity with the same independent and dependent variables. Study A had a sample size of 500 and the p-value was calculated at .002. Study B also had a sample size of 500 and the p-value was calculated at .033. Which study had the smaller effect size?
Study B
A researcher conducts two studies on relational satisfaction with the same independent and dependent variables. After conducting a two-sample t-test, Study A was found to have an effect size of .65 and a p-value of .0001. Study B was found to have an effect size of .65 and a p-value of .076. Which study has the smaller sample size?
Study B
When Pearson's r is negative, variables are said to have an "inverse relationship." What does this mean?
That when X increases, Y decreases
A bivariate analysis typically focuses on...
The association of two variables
What is the null hypothesis for the chi-squared goodness of fit test?
The distribution of frequencies will match a hypothesized pattern of expected scores or frequencies
If variance is very low
The individuals in the data set are very similar to each other
Which of the following illustrates a negative correlation?
The more often a person visits the dentist, the fewer cavities they have.
According to the Central Limit Theorem, it is safe to assume that given an infinite number of samples:
The shape of the distribution of sample means will approximate a normal curve if the sample size (n) used to calculate each mean is > 30.
If a person has a middling score on X but a very high score on Y, what would their effect on the regression equation be?
They would raise the intercept but not change the slope
Which of the following situations is appropriate for using a chi-squared test?
To examine the relationship between major and graduation status at a university
Pooled variance is calculated for which test?
Two-sample t-tests
A chi-squared test is conducted:
When the independent and dependent variables are nominal/ordinal data
A two-sample t-test is conducted:
When two sample means are being compared
Which is generally more accurate (in the statistical sense): a point estimate or a confidence interval?
a confidence interval
The sample mean is ________ and a confidence interval for the mean is _______.
a descriptive statistic; an inferential statistic
In order to understand exactly how strong the relationship is between two categorical variables in a chi-squared test for independence, a research should use...
a measure of effect size like the phi coefficient
Which is generally more precise (in the statistical sense): a point estimate or a confidence interval?
a point estimate
Which is more precise (in the statistical sense): a point estimate or a confidence interval?
a point estimate
When we talk about "estimation" in statistics, what is it that is being estimated?
a population parameter
If a person's blood sample tests positive for a disease when, in fact, the person does not have the disease, then...
a type one error has occurred
When the population mean and variance is known, it is most appropriate to use:
a z-test
This predictor variable in this chart...
age
In a normal distribution, which measure of central tendency has the highest value?
all are the same
If a web marketer compares the effectiveness of two online ads in getting clicks by gathering data from 3 million Internet shoppers, the population of interest is...
all internet shoppers
Which of the following null hypothesis statistical tests require calculating degrees of freedom?
all of these tests: one-sample t test chi-squared two-sample t-test
For which measures is it possible to compute a confidence interval?
any population parameter
A sampling distribution can be calculated for...
any sample statistic
Compared to a mesokurtic distribution, the tails of a leptokurtic distribution...
are longer
When people who score low on one variable tend to score low on another variable, then those two variables...
are positively correlated
A histogram is not appropriate when the data are...
at the nominal or ordinal level of measurement
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...
be narrower
If a distribution of raw scores has a strong negative skew, then, given a sufficiently large n, the sampling distribution of means for that distribution will...
be normal
As the standard deviation for a distribution increases, then the corresponding confidence interval will...
become wider
When the range of confidence for a confidence interval becomes higher - from 80% to 99%, for example - then the confidence interval will...
become wider
A distribution with two distinct peaks can be described as...
bimodal
This distribution can be described as...
bimodal
When a histogram or polygon chart for a quantitative variable has two distinct peaks, then the distribution is referred to as _____.
bimodal
A chi-squared test is conducted when...
both of the variables are nominal/ordinal data.
A chart of this type is called a...
box plot
A major advantage of the chi-squared tests is that they...
can be used with any level of measurement
What is the mean for these data? 3, 1, 2, 5+, 2, 4
cannot be calculated
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 probability distribution that is used in the chi-squared test is the...
chi-squared distribution
If Cohen's d is very small, the two means are ______________ each other
close to
If the dots on a scatterplot are spread out randomly, the researcher would report the correlation as:
close to zero
The variable that is measured as the outcome in an experiment is called the _____ variable.
dependable
inferential statistics are typically contrasted with ___ statistics
descriptive
A question that asks a person how strong their motivations for religious participation are using a 1-7 rating scale is at _____ level of measurement.
either the ordinal or the interval
In calculating a chi-squared tests, the observed frequencies in each category are compared to...
expected frequencies
A Type I error is also called...
false positive
Which of the following distributions is mesokurtic?
first peak
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
Correlations (using the Pearson product moment correlation coefficient) may be uninterpretable and inappropriate if the data...
have a non-linear relationship
Compared to a mesokurtic distribution, the peak of platykurtic distribution is...
higher
A chart of this type is called a...
histogram
A score's frequency is determined by...
how often it occurs in the data set.
If a researcher believes that the null hypothesis is false and wants to have the greatest chance of rejecting it with their study, then which of the following would make it more likely that the null hypothesis would be rejected?
increasing n
In an experiment, the variable that the researcher manipulates is called the _____ variable.
independent
"Estimation" refers to a class of...
inferential statistics
The chi-squared tests are...
inferential statistics/procedures.
If the number of games a team has lost in a season is subtracted from the number of games that they won in that season, the resulting variable would be at the _____ level of measurement.
interval
Temperature in celsius or Fahrenheit (but not Kelvin) is measured at which level of measurement?
interval
What is the minimum level of measurement needed to calculate the mean?
interval
What is the minimum level of measurement to calculate a Pearson's r correlation coefficient?
interval
Which is the lowest level of measurement needed to calculate a mean?
interval
Which measure of variation is LEAST sensitive to outliers?
iqr
The standard normal distribution...
is a bell curve with M = 0 and SD = 1.
For a normal distribution, skewness...
is equal to 0
In a two-tailed or non-directional test, if the critical value has a greater absolute value than the observed (or test) value does, the the null hypothesis...
is not rejected (i.e. , retained)
A uniform distribution...
is platykurtic.
How is a confidence interval affected when the sample size increases?
it becomes narrower
One reason that researchers nearly always gather data from samples of participants instead of entire populations is because..
it can be impractical or even impossible to study populations
How is a point estimate affected when the sample size increases?
it does not change
How is the point estimate affected when the sample standard deviation increases?
it does not change
One reason that researchers nearly always gather data from samples of participants instead of populations is because..
it is easier to gather data from samples than populations
When calculating an effect size for the z-test...
it is most common to use Cohen's d.
A researcher who wants to use a z-test to compare a sample mean to a population mean must first...
know the population standard deviation
In order to compute a one-sample z-test you must...
know the population standard deviation
Which of the following is not true about the normal distribution?
kurtosis = 1
A narrow distribution that is sharply pointed in the middle and that has many outliers is called...
leptokurtic
Imagine that a researcher is interested in whether residents in his local area have higher levels of well-being than the national average. What would be an appropriate alternate hypothesis for a one-tailed or directional z-test for this test?
local residents average > national average
If r = -.4, then the people who have _____ values on the predictor variable generally have _____ values on the outcome variable.
lower, higher
If r = .65, then the members in a sample who have _____ values on the independent variable have _____ values on the dependent variable.
lower, lower
If r = .65, then the members in a sample who have __________ values on the independent variable have ____________ values on the dependent variable.
lower, lower
which of the following is a defining characteristic of experiments?
manipulations
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 affected by outliers?
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 distribution of all possible sample variances - if n is sufficiently large (e.g., n > 30) - will be...
mesokurtic
The normal distribution is...
mesokurtic
Which of the following distributions is leptokurtic?
middle peak
In a negatively skewed distribution, which measure will generally have the highest value?
mode
What is the minimal level of data required to calculate a mode?
mode
Which measure of central tendency is LEAST efficient?
mode
Which measure of central tendency works for nominal variables?
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
If the dots on a scatterplot generally extend from the top left to the bottom right of the diagram but are very widely spread out, the researcher would report the correlation as...
negative but weak
A normal distribution generally has _____ skew.
no
A question that asks a person which religion (if any) they identify with is at the _____ level of measurement.
nominal
A variable that classifies people into racial or ethnic groups is what level of measurement?
nominal
Gender is an example of 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 coded as Male = 1 or Female = 2, 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
The respondent's gender is typically recorded as a(n) _____ variable.
nominal
What is the minimum level of measurement needed to calculate the mode?
nominal
What is the minimum level of measurement required for either of the chi-squared tests?
nominal
A frequency bar graph would be most appropriate for which measurement scales?
nominal or ordinal
Which of the following is always true for "statistically significant" results?
none of the above
If a research conducts a z-test and does not reject the null hypothesis, then...
none of the choices are correct
Correlations may not be interpretable for which type of relationship?
nonlinear
The relationship in this scatterplot is... (two lines kinda together going down with lots of dots)
nonlinear
As the size of samples (n) in a sampling distribution increases, the shape of that distribution becomes more...
normal
The Central Limit Theorem states that the shape of a sampling distribution becomes closer to what shape as the number of sample means in the distribution increases?
normal
The central limit theorem says that when all possible samples of a sufficient size are taken from a population and their means are charted, that distribution of means will be...
normally distributed
If a person has a z-score of 1 on a test, then their score is...
one standard deviation above the mean
A univariate analysis typically focuses on...
one variable at a time
A question that asks whether a person believes they are more creative, less creative, or just as creative as other people is at the _____ level of measurement.
ordinal
In a sample of women, the number of children that each woman has is an example of which level of measurement?
ordinal
Military ranks are an example of what level of measurement?
ordinal
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
A confidence interval specifies a range of values for a parameter estimate, whereas a(n) _____ specifies just a single value for that parameter.
point estimate
If you can use only one number to estimate a population parameter, then the best value is a...
point estimate
A sample is a part of a larger...
population
Which is bigger: a sample or a population?
population
What does the symbol σ2 stand for?
population variance
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
If a positively skewed distribution with a mean of 100 and a standard deviation of 15 is standardized, then the shape of the new distribution will be...
positively skewed
The distribution below is...
positively skewed
This distribution is...
positively skewed
Which of the following is true about regression towards the mean?
predicted Y values will not always be perfect unless r = 1
A histogram is appropriate when the data are...
quantitative
When data are negatively skewed, which measure of variability is most appropriate?
quartiles (such as the interquartile range)
When open-ended scores are present in the data, which measure of variability is most appropriate?
quartiles (such as the interquartile range)
What is the non-directional null hypothesis for correlation?
r = 0 (or rho = 0)
What type of variability is used to screen for data entry errors and outliers?
range
Which measure of variation is most influenced by outliers?
range
Which of the following is most sensitive to extreme scores?
range
The three measures of variability are:
range, variance, standard deviation
A question that asks how many times a person attends religious services each year is at the _____ level of measurement.
ratio
A variable that records how many seconds it take for a person to spell a word backwards is at the _____ level of measurement.
ratio
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 in a school each year is an example of which level of measurement?
ratio
Which level of measurement has a true zero point?
ratio
A researcher uses alpha as the criteria or critical value for the maximum probability of incorrectly rejecting the null hypothesis. She conducts a z-test with alpha = .05 and finds the p-value is .02. The researcher should
reject the null hypothesis
When a distribution of raw scores is converted to z-scores, the shape of the distributions...
remains the same.
The difference between a predicted Y score and an actual observed Y score is known as the
residual
The difference between a predicted Y score and an actual observed Y score is known as the...
residual
When a regression equation doesn't predict a person's score perfectly, then the difference between their predicted score and their actual score is the...
residual
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 (fail to reject) the null hypothesis
If a researcher is using an alpha of .05 for a z-test and gets an observed (or test) p-value of .23, then the researcher should...
retain (i.e. fail to reject) the null hypothesis
If a researcher is using an critical value of ±1.96 for a z-test and gets an observed (or test) z of -1.73, then the researcher should...
retain (i.e. fail to reject) the null hypothesis
If we use alpha as the criteria or critical value for the maximum probability of incorrectly rejecting the null hypothesis, then in an ANOVA test where alpha = .01 and the calculated p-value = .20, we should:
retain the hypothesis
If a researcher is able to survey 99% of all students enrolled in statistics classes at a college, then that researcher has gathered data from a(n)...
sample
Imagine two samples that are drawn from the same population and measure the same variables in the same way. Sample A has a larger confidence interval than Sample B does. Which sample likely has the larger n?
sample B
Which measure requires a degrees of freedom calculation?
sample variance
Most data sets in social science studies are from _____________.
samples
If a researcher conducts a chi-squared test for independence using an alpha of .05 and gets an observed p-value of .04, then she...
should reject the null hypothesis
If a researcher conducts a chi-squared goodness-of-fit test using an alpha of .05 and gets an observed p-value of .10, then she..
should retain (fail to reject) the null hypothesis
If a researcher conducts a chi-squared test for independence using an alpha of .01 and gets an observed p-value of .04, then he...
should retain (fail to reject) the null hypothesis
What are the values of skewness and kurtosis for a normal distribution?
skewness = 0 and kurtosis = 0
A population can never be...
smaller than one of its samples
For a normal distribution, which measure of variability is most efficient (in the statistical sense)?
standard deviation
Which of the following is NOT a measure of central tendency?
standard deviation
As the mean for a distribution increases, then the width of the corresponding confidence interval will...
stay the same
As the mean for a sample becomes greater, the width of the corresponding confidence interval will...
stay the same
The closer Pearson's r correlations are to -1 or 1, the ___________ the relationship between X and Y is.
stronger
In an experiment that looks at the effect of different teaching methods on student learning, the independent variable is...
teaching method
In a study that looks at the relationship between gender and college major, a statistically significant chi-squared test for independence would mean...
that the distribution of college major varied by gender and the distribution of genders varied by college major.
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.
What does it mean when the result of a z-test is called "statistically significant"?
the alpha value was greater than the p value
In hypothesis testing, if the null hypothesis has been rejected, what hypothesis do we assume?
the alternative hypothesis
Which version of the chi-squared test is good for examining the relationship between two variables?
the chi-squared test for independence
What is one important difference between a point estimate and a confidence interval?
the confidence interval gives two numbers instead of one
The word "independence" in the chi-squared test for independence means...
the distribution of frequencies on the outcome/dependent variable is unrelated to the categories of the predictor/independent variable.
In a two-sample t-test, what is the grouping variable?
the independent variable
In a positively skewed distribution, which measure of central tendency has the highest value?
the mean
According to the Central Limit Theorem, the mean of the sampling distribution of means - ��¯ - ( will equal...ux-) will equal...
the mean of the original population
What does the label "Q2" refer to?
the median score or the 50th percentile
If a regression equation is calculated for a sample of data and then a person who is an outlier on both X and Y is added, what would likely happen to the regression equation?
the new score would likely change both the intercept and the slope
Which of the following statements below is inappropriate when discussing results of statistical significance tests?
the null hypothesis has been proven true
If we use alpha as the criteria or critical value for the maximum probability of incorrectly rejecting the null hypothesis, then when the p-value is less than alpha:
the null hypothesis is rejected
In a two-sample t-test, we establish our critical value as +1.96. Our observed value (test value) was calculated as +2.10. This always means:
the null hypothesis is rejected
In null hypothesis testing, if the critical value is less extreme than the observed value (i.e., test value), then:
the null hypothesis is rejected
If a researcher wants to test whether an experimental group is different from the general population, the she would test...
the null hypothesis of no difference between the group and the population
What would be the advantage of increasing n in null hypothesis significance testing?
the null hypothesis would be more likely to be rejected
The most common measure of effect size for the chi-squared test for independence is...
the phi coefficient
The standard error of a sampling distribution is a function of two things:
the population standard deviation and the sample size
If you draw a picture of the null distribution with the critical values and regions of rejection marked, then the alpha level is represented by...
the proportion of the distribution in the regions of rejection
The blue box in this chart represents...
the range for the middle 50% of scores
In which of the following situations is the median an appropriate measure of central tendency?
the researcher has ordinal data
The z-test is appropriate when...
the researcher knows the population mean and variance/standard deviation
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 vertical distance between a person's predicted score on Y and their actual score on Y is called _____ and it signifies _____.
the residual; error in prediction
If a researcher is using alpha = .05 and gets a p-value for the z-test of p = .02, then...
the results are unlikely to occur by chance is the null hypothesis is true
A Type I error occurs when...
the sample data lead us to reject a null hypothesis that is true.
A Type II error occurs when...
the sample data lead us to retain (i.e. fail to reject) a null hypothesis that is false
A point estimate for the population mean is based on...
the sample mean
The effect size is calculated as d = .89. What does this mean?
the sample mean is .89 stand deviations away from the population mean
If a researcher is comparing a sample mean to a population mean and gets Cohen's d = -2.0, this means that...
the sample mean is two standard deviations below the population mean
When calculating an effect size for the z-test...
the sample size is irrelevant.
A problem with using the sample standard deviation to estimate the population standard deviation is
the sample standard deviation underestimates the population standard deviation
The distribution of all possible sample means (of a given size) is called...
the sampling distribution of means
The distribution of all possible samples of a given size (e.g., n = 54 or n = 117) are taken from a population and their means are charted, that distribution is known as...
the sampling distribution of means
The distribution of all possible sample variances (of a given sample size) is called...
the sampling distribution of variance
What is the relationship between the standard deviation and the variance?
the standard deviation is the square root of the variance
The standard error is...
the standard deviation of a sampling distribution
If a person were to create a sampling distribution for sample standard deviations, then the mean of that distribution would be equal to...
the standard deviation of the original distribution
If Cohen's d = 2.25, then which of the following is always true?
there are 2.25 standard deviations between the two sample means
The chi-squared tests are called "non-parametric" tests because...
they do not make assumptions about population parameters
If the formula for the population standard deviation were used with sample data, then result would be...
too small
After a researcher rejects the null hypothesis, she needs to be aware of
type 1 error
The sample mean is a(n) _________________ of the population mean.
unbiased point estimate
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 the dots on a scatterplot generally extend from the bottom left to the upper right of the diagram but are very widely spread out, the researcher would report the correlation as:
weak and positive
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
When scores in a data set are very close to one another, then the variance...
will be close to 0.
If scores in a data set are very different from each other, then the standard deviation...
will be high
When conducting a z-test, which probability distribution would be appropriate to use?
z-distribution
Which inferential test does NOT require a degrees of freedom calculation?
z-test
If X and Y in a regression equation are both expressed as z scores -zx and zy- then what can never happen?
zy>zx
The equation for the standard error of a sampling distribution is...
ø/square root of n
Mean of the sampling distribution of the mean
μx̄
What is the symbol for the standard error?
σx
