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Quiz 3 module 3
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Perguntas do quiz (66)
1How can categorical data with one variable be summarised?
- AFrequencies, proportions or percentages
- BCross-tabulation (contingency table)
2How can categorical data with two variables be summarised?
- AFrequencies, proportions or percentages
- BCross-tabulation (contingency table)
3What is the way of graphing one categorical variable?
- ABar graph
- BSide-by-side bar graph
- Cpie charts
4What is the way of graphing two categorical variables?
- ASide-by-side bar graph
- Bpie charts
- CBar graph
5With categorical data, we aim to investigate the differences between variables
- AVerdadeiro
- BFalso
6What is the test for one categorical variable
- Achi-squared goodness of fit test
- BA two-way table test
- CT-test
- DTwo-sample t-test
7What is a chi-squared goodness of fit test used to test?
- Athe hypothesis
- Bthe range of data
- Cvariance
8If the Ho is: {the number of individuals presenting at the A&E ward of the Royal Brisbane Hospital is evenly distributed across all age groups} What would we expect the results to show?
- Ano difference between the groups
- BA difference between the groups
9Under the one-sample chi-squared goodness of fit test, when do we retain (accept) Ho?
- AIf the difference between the observed frequency (fo) and the expected frequency (fe) is small
- BIf the difference between the observed frequency (fo) and the expected frequency (fe) is large
10What is the test statistic?
- AThe discrepancy between the data and what is expected under the null hypothesis
- BA statistical test used to quantify the discrepancy between the expected (fe) and observed (f0) frequencies
11What is the one-sample chi-squared test?
- AA statistical test used to quantify the discrepancy between the expected (fe) and observed (f0) frequencies
- BThe test statistic
- Cis a t-test and uses a known distribution (normal distribution) or a t-distribution
12What is the equation for calculating the test statistic?
- A(observed - expected)/precision
- B(expected - observed)/precision
13How many degrees of freedom are there in a Chi-square analysis performed on a contingency table with 2 rows and 2 columns?
- A(number of rows - 1) x (number of columns - 1)
= 1 - B(number of rows + 1) x (number of columns + 1)
- A(number of rows - 1) x (number of columns - 1)
14I can use Fisher's Exact test instead of Chi-square when I have a 2x2 table, irrespective of the expected cell counts.
- AVerdadeiro
- BFalso
15How many degrees of freedom are there in a Chi-square analysis if I am comparing two variables, one with three categories and the other with four categories?
- A(number of categories in variable 1 - 1) x (number of categories in variable 2 - 1)
- B(number of categories in variable 1 + 1) x (number of categories in variable 2 + 1)
16Which of the following hypothesis could be tested using a Chi-square Test of Independence?
- AH0: The proportion of males who smoked is the same as that reported 10 years ago in a sample of similar aged individuals.
H1: The proportion of males who smoked is different to that reported 10 years ago in a sample of similar aged individuals. - BH0: The proportion of males who smoked is the same as the proportion of females who smoked.
H1: The proportion of males who smoked is different to the proportion of females who smoked. - CH0: The average age of male smokers is the same as average of female smokers.
H1: The average age of male smokers is different to the average of female smokers - D
H0: The proportion of males who smoked is lower than the proportion of females who smoked.
H1: The proportion of males who smoked is higher than the proportion of females who smoked.
- AH0: The proportion of males who smoked is the same as that reported 10 years ago in a sample of similar aged individuals.
17True or false? I would use a Chi-square Goodness of Fit test if I want to look for an association between two ordinal variabls in my data set.
- AVerdadeiro
- BFalso
18True or false? The results I get in R Commander for a Chi-square analysis change if I switch which variable is the row and which is the column in the contingency table.
- AVerdadeiro
- BFalso
19True or false? I would use a Chi-square Test of Independence if I want to look for an association between two continuous variabls in my data set.
- AVerdadeiro
- BFalso
20
How many degrees of freedom are there in a Chi-square analysis if I am comparing two variables, one with three categories and the other with four categories?- A4
- B5
- C6
21The chi-squared goodness of fit test is the statistical test to quantify the discrepancy between the observed and expected frequencies?
- AVerdadeiro
- BFalso
22In a chi-squared goodness of fit test the degrees of freedom is calculated using the equation (k - 1) where 'k' is the number of categories
- AVerdadeiro
- BFalso
23If observed and expected are the same or close to each other, we expect the chi-squared (x^2) value to be:
- AReally small or zero
- BLarge
24A large chi-squared value indicates that the observed is quite different from the expected under Ho.
- AVerdadeiro
- BFalso
25Chi-squared only has one parameter – the degree of freedom (df).
- AVerdadeiro
- BFalso
26the df controls the shape of the distribution.
- AVerdadeiro
- BFalso
27'k' is the number of categories
- AVerdadeiro
- BFalso
28What are ways to summarise data for categorical data
- Anumerical summeries
- Bgraphical
29For categorical data, the test statistic is the chi-squared test value
- AVerdadeiro
- BFalso
30p>0.05
- ADo not reject Ho
- BReject Ho
31How is the association between two categorical variables tested?
- AGoodness of fit test
- Bchi squared test of independance
32For the chi-squared test of independance, you have to calculate the test statistic for each cell in the table (excluding row and column totals)
- AVerdadeiro
- BFalso
33In a x^2 test of independance, what does a large positive value for x^2 indicate about Ho?
- Athere is a difference between the two groups
- Bthere is no difference between the two groups
34expected frquency = (column total x row total)/ overall total
- AVerdadeiro
- BFalso
35For a x^2 distribution, the shape changes as the df changes
- AVerdadeiro
- BFalso
36If the pvalue is less than zero, we reject Ho
- AVerdadeiro
- BFalso
37x^2 independence what are the assumptions
- Aobservational units are independant
- Bexpected cell counts should be greater than 5
38If the expected values are less than 5
- AHave to use fisher’s exact test. Also could combine categories together, so the expected numbers in the groups are greater than 5.
- BUse chi squared test
- AHave to use fisher’s exact test. Also could combine categories together, so the expected numbers in the groups are greater than 5.
39What are other ways of representing relationships among categorical variables
- A- difference in proportions of specified outcomes
- B- relative risk
- C- odds ratio
40Can a chi-squared test be used if there is no independance?
- Ayes
- Bno
41What is McNemar's test of association used for?
- A2 x 2 tables
- Bone sample
42No cell should have an expected frequency of less than 5
- AVerdadeiro
- BFalso
43What is a one sample t-test?
- AComparing one mean to an external population
- BComparing two means
44What is a two sample t test
- AComparing two independant means
- BComparing means for paired values
45What is a paired t-test
- AComparing means for paired values
- Bcoomparing external population
46parametric test is used for continuous data
- AVerdadeiro
- BFalso
47Are the data normally distributed? You look at the median and the variance of values between the two samples
- AVerdadeiro
- BFalso
48Levene's test - for continuous data
- AVerdadeiro
- BFalso
49mann-whitney test: compares medians of two samples of continuous data
- AVerdadeiro
- BFalso
50What do we do if we have >2 groups to compare?
- AOne-way analysis of variance (ANOVA)
- BChi-squared goodness of fit test
- CChi-squared test of independance
51What are the assumptions of the ANOVA test?
- ANormally distributed dependent variable (OR large enough sample size in each group)
- B Independence among observations (both within and between groups)
- CEqual variances
52What are the hypotheses for an ANOVA test?
- AHo: All group population means are the same
- BH1: At least one group's population mean differs
- CH1: All group population means are different
- DHo: There is no association between the group population means
- EH1: There is an association between the group population means
53A ANOVA test analyses the variability of the data
- AVerdadeiro
- BFalso
54ANOVA TEST: Variation is due to:
- ADifferences between the groups of interest
- BRandom variation within each group (or data error)
55ANOVA - little difference between means or groups makes it difficult to conclude a difference between groups
- AVerdadeiro
- BFalso
56What is balanced data?
- ASize of groups is equal
- BSize of groups is different
- CSize of groups is undetermined
57What is unbalanced data?
- AGroup sizes are not equal
- BGroup sizes are equal
58ANOVA TEST: total variation equation: Total SS (sum of squares) = Group SS + Error SS
- AVerdadeiro
- BFalso
59To account for different df in anova test, the SS has to be converted to MS (mean squares)
- AVerdadeiro
- BFalso
60The ratio between two variances is called the variance ration (F in R commander - the test statistic for ANOVA)
- AVerdadeiro
- BFalso
61ANOVA test: P value<0.05
- Areject Ho
- Baccept Ho
62F distribution in ANOVA test relies on df
- AVerdadeiro
- BFalso
63What test is used if in ANOVA Ho is rejected?
- APost-hoc
- BChi-squared
- CT-test
64Post-‐hoc
tests
are
formulated
so
that
the
overall
type
I
error
aqer
all
comparisons
is
0.05- AVerdadeiro
- BFalso
65/if data are not normally distributed in ANOVA what test is used?
- Akruskal-wallis
- Bt-test
- Cpost-hoc
66Generally
we
need
about
4
times
as
much
variaKon
between
groups
as
within
groups
to
conclude
differences
exist
between
groups
-‐>
F
~
4- AVerdadeiro
- BFalso
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