STAT 121 QUESTIONS WITH VERIFIED ANSWERS
What statistical method can provide a prediction? - Answers - regression analysis
What test should be used if comparing the proportions for 2 separate sets of data? -
Answers - A 2-sample z test on proportion
Analysis of variance tests are generally performed to compare? - Answers - 3 or more
means
If 2 mean times are to be compared, what procedure should be used to analyze the
data? - Answers - 2-sample t test
If a sampling is done separately in five different categories, and a proportion computed
for each, what procedure should be used to analyze the data? - Answers - a Chi-square
test
What procedure should be used to analyze the data when testing the mean of one
sample tested for a monitoring check? - Answers - a one-sample t test
what procedure should be used if taking only one sample with a categorical response
variable and testing whether the proportion exceeds a certain limit? - Answers - one-
sample z test for proportion
What test should be used to make a prediction based on one sample with 2 different
quantitative measurements? - Answers - Regression analysis
what procedure should be used to compare the means of 3 different treatment groups
with a categorical explanatory variable and a quantitative response variable? - Answers
- Analysis of variance (ANOVA)
What procedure should be used to compare 2 means from a completely randomized
experiment with 2 treatments and a quantitative response variable? - Answers - a 2
sample test
What procedure should be used to analyze the data from an experiment where the
same person is given 2 types of treatments? - Answers - matched pairs t test
For a single sample taken with 2 questions asked with both categorical explanatory and
response variables, what type of procedure should be used to analyze the data? -
Answers - a chi-square test
,Why do we recommend using ANOVA to compare 4 means rather than performing 6
separate two sample t tests? - Answers - to prevent inflating the overall "alpha" or type I
error rate
What numerical summary is used for categorical (qualitative) data? - Answers -
proportion
symbol p - Answers - proportion or percentage of the true population
symbol p "hat" - Answers - symbol for sample proportion
As n increases, the standard deviation of the sample proportion? - Answers - decreases
as n increases, the shape of the sampling distribution of the sample proportion
becomes? - Answers - more Normal
parameters for a Normal sample size - Answers - np > 10
n(1-p) > 10
the mean of the sampling distribution of p "hat" equals? - Answers - the population
proportion, regardless of sample size.
For samples if size 200, sampling distributions for p "hat" are more bell shaped when p
is close to? - Answers - 0.5 versus zero or one
Margin of error gives us an idea of? - Answers - how far our point estimate might be
from the parameter it estimates
When calculating a confidence interval for P, what do we check in order to determine
whether the sample size is large enough for the sampling distribution of p "hat" to be
approximately Normal? - Answers - np > 10 and
n (1-p) > 10
We use facts about the sampling distribution of p "hat" to obtain the P-value for testing?
- Answers - Ho: p = po
Where is the P-value in the sampling distribution of p "hat"? - Answers - the area in the
tail defined by Ha of the sampling distribution of p "hat."
What is the symbol for the hypothesized value for p when testing Ho: p = po? - Answers
- po
What is the generic formula for a test statistic? - Answers - estimate - hypothesized
value/standard deviation under Ho
, When testing Ho: p = po, what do we check to determine whether the sample size is
large enough for the sampling distribution of p "hat" to be approximately Normal? -
Answers - npo > 10 and
n (1-po) > 10
What is the standardized test statistic? - Answers - z
What is the value of p* that will give us the most conservative estimate for sample size?
or What value should we use when we have no other information about the value of p? -
Answers - 0.50
What parameter do we estimate in order to compare the proportions from 2
populations? - Answers - p1 - p2
In words, how do we describe ^p1 - ^p2? - Answers - the difference between the 2
sample proportions
we use the 2 sample z procedure to compare the proportions of? - Answers - 2
populations or 2 treatments
Ho = p1 - p2 is equivalent to? - Answers - Ho: p1 = p2
When both the explanatory variable and the response variable are categorical and each
has only 2 possible categories, we compare? - Answers - 2 proportions
Data can always be summarized in a 2x2 table when? - Answers - performing a 2
sample z procedure on proportions
When comparing 2 proportions, the parameter is p1 - p2 and the statistic is? - Answers -
^p1 - ^p2
What is the biggest problem with multiple comparisons (multiple tests)? - Answers - the
overall alpha, risk of type I error, is inflated, increasing the probability of rejecting at
least one hypothesis due to chance, and the greater the risk of declaring significance for
at least one test due only to chance.
If we are testing whether the row variable is associated with the column variable, what is
the appropriate alternative hypothesis that should be used for a chi-square test to
control the overall alpha? - Answers - Ha: Population distributions are all different
When using the chi square test, what are the conditions of the response and
explanatory variables? - Answers - both must be categorical
What are "observed counts" - Answers - the actual counts we obtain by counting the
number of observations in each category in the data
What statistical method can provide a prediction? - Answers - regression analysis
What test should be used if comparing the proportions for 2 separate sets of data? -
Answers - A 2-sample z test on proportion
Analysis of variance tests are generally performed to compare? - Answers - 3 or more
means
If 2 mean times are to be compared, what procedure should be used to analyze the
data? - Answers - 2-sample t test
If a sampling is done separately in five different categories, and a proportion computed
for each, what procedure should be used to analyze the data? - Answers - a Chi-square
test
What procedure should be used to analyze the data when testing the mean of one
sample tested for a monitoring check? - Answers - a one-sample t test
what procedure should be used if taking only one sample with a categorical response
variable and testing whether the proportion exceeds a certain limit? - Answers - one-
sample z test for proportion
What test should be used to make a prediction based on one sample with 2 different
quantitative measurements? - Answers - Regression analysis
what procedure should be used to compare the means of 3 different treatment groups
with a categorical explanatory variable and a quantitative response variable? - Answers
- Analysis of variance (ANOVA)
What procedure should be used to compare 2 means from a completely randomized
experiment with 2 treatments and a quantitative response variable? - Answers - a 2
sample test
What procedure should be used to analyze the data from an experiment where the
same person is given 2 types of treatments? - Answers - matched pairs t test
For a single sample taken with 2 questions asked with both categorical explanatory and
response variables, what type of procedure should be used to analyze the data? -
Answers - a chi-square test
,Why do we recommend using ANOVA to compare 4 means rather than performing 6
separate two sample t tests? - Answers - to prevent inflating the overall "alpha" or type I
error rate
What numerical summary is used for categorical (qualitative) data? - Answers -
proportion
symbol p - Answers - proportion or percentage of the true population
symbol p "hat" - Answers - symbol for sample proportion
As n increases, the standard deviation of the sample proportion? - Answers - decreases
as n increases, the shape of the sampling distribution of the sample proportion
becomes? - Answers - more Normal
parameters for a Normal sample size - Answers - np > 10
n(1-p) > 10
the mean of the sampling distribution of p "hat" equals? - Answers - the population
proportion, regardless of sample size.
For samples if size 200, sampling distributions for p "hat" are more bell shaped when p
is close to? - Answers - 0.5 versus zero or one
Margin of error gives us an idea of? - Answers - how far our point estimate might be
from the parameter it estimates
When calculating a confidence interval for P, what do we check in order to determine
whether the sample size is large enough for the sampling distribution of p "hat" to be
approximately Normal? - Answers - np > 10 and
n (1-p) > 10
We use facts about the sampling distribution of p "hat" to obtain the P-value for testing?
- Answers - Ho: p = po
Where is the P-value in the sampling distribution of p "hat"? - Answers - the area in the
tail defined by Ha of the sampling distribution of p "hat."
What is the symbol for the hypothesized value for p when testing Ho: p = po? - Answers
- po
What is the generic formula for a test statistic? - Answers - estimate - hypothesized
value/standard deviation under Ho
, When testing Ho: p = po, what do we check to determine whether the sample size is
large enough for the sampling distribution of p "hat" to be approximately Normal? -
Answers - npo > 10 and
n (1-po) > 10
What is the standardized test statistic? - Answers - z
What is the value of p* that will give us the most conservative estimate for sample size?
or What value should we use when we have no other information about the value of p? -
Answers - 0.50
What parameter do we estimate in order to compare the proportions from 2
populations? - Answers - p1 - p2
In words, how do we describe ^p1 - ^p2? - Answers - the difference between the 2
sample proportions
we use the 2 sample z procedure to compare the proportions of? - Answers - 2
populations or 2 treatments
Ho = p1 - p2 is equivalent to? - Answers - Ho: p1 = p2
When both the explanatory variable and the response variable are categorical and each
has only 2 possible categories, we compare? - Answers - 2 proportions
Data can always be summarized in a 2x2 table when? - Answers - performing a 2
sample z procedure on proportions
When comparing 2 proportions, the parameter is p1 - p2 and the statistic is? - Answers -
^p1 - ^p2
What is the biggest problem with multiple comparisons (multiple tests)? - Answers - the
overall alpha, risk of type I error, is inflated, increasing the probability of rejecting at
least one hypothesis due to chance, and the greater the risk of declaring significance for
at least one test due only to chance.
If we are testing whether the row variable is associated with the column variable, what is
the appropriate alternative hypothesis that should be used for a chi-square test to
control the overall alpha? - Answers - Ha: Population distributions are all different
When using the chi square test, what are the conditions of the response and
explanatory variables? - Answers - both must be categorical
What are "observed counts" - Answers - the actual counts we obtain by counting the
number of observations in each category in the data
