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Return to Research Methods Using R 1e Student Resources
Chapter 7 Multiple choice questions
Quiz Content
*
not completed
.
Download the data file for the multiple-choice questions for Chapter 7
, and open it in
R.
The data frame
RTlmm
contains reaction time data for the lexical decision experiment described on pages 90 – 95 (though note that the reaction times are different from those given in Table 7.2).
Run a mixed effects model with random intercepts using the
lmerTest
package. Wordtype and validity are fixed effects, and subject and item are random effects. What is the t-value for the main effect of word type?
18.48
correct
incorrect
10.90
correct
incorrect
25.11
correct
incorrect
-13.17
correct
incorrect
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not completed
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For the analysis described in Question 1, what is the F-ratio for the interaction between word type and validity?
118.77
correct
incorrect
630.36
correct
incorrect
173.45
correct
incorrect
-13.17
correct
incorrect
*
not completed
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For the analysis described in Question 1, is item a significant predictor, and what is its AIC score?
AIC = 16773, is a significant predictor
correct
incorrect
AIC = 16773, not a significant predictor
correct
incorrect
AIC = 17833, is a significant predictor
correct
incorrect
AIC = 17833, not a significant predictor
correct
incorrect
*
not completed
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For the analysis described in Question 1, what is the conditional R
^{2}
value for the model?
0.29
correct
incorrect
16445.31
correct
incorrect
-0.95
correct
incorrect
0.76
correct
incorrect
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not completed
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Change the model so that item is no longer included as a random effect. Is the fit significantly poorer for this model?
Yes, because the marginal R2 value is lower
correct
incorrect
Yes, because the conditional R2 value is lower
correct
incorrect
No, because the main effects and interaction remain significant
correct
incorrect
Yes, because a chi-square test comparing the models is significant
correct
incorrect
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not completed
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The data frame
frogdata
contains data showing estimates of frogspawn in different ponds across several national parks. The size of each pond is also recorded. Ignoring each pond's location, run a linear regression on these data. Does pond size predict the amount of spawn?
Yes, because the regression is significant (
p
< 0.05)
correct
incorrect
No, because the regression is not significant (
p
> 0.05)
correct
incorrect
Yes, because the regression slope is positive
correct
incorrect
No, because the regression slope is negative
correct
incorrect
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not completed
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Now run a mixed effects model on the frogspawn data, with parkID as a random effect, allowing random intercepts and slopes. What is the F-ratio and p-value for the effect of pondsize?
F = 135.79,
p
= 9*10
^{-16}
correct
incorrect
F = 11.65,
p
= 9*10
^{-16}
correct
incorrect
F = 3.53,
p
= 0.013
correct
incorrect
F = 49.27,
p
= 9*10
^{-16}
correct
incorrect
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not completed
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Run two further mixed effects models with either random slopes or random intercepts. Compared to the model with random intercepts and slopes, which model changes the outcome most substantially?
The random intercepts model produces a much better fit
correct
incorrect
The random slopes model produces a much better fit
correct
incorrect
The random intercepts model produces a much poorer fit
correct
incorrect
The random slopes model produces a much poorer fit
correct
incorrect
*
not completed
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Explore the coefficients for the full model with random intercepts and random slopes (from question 7). Which park location has the largest intercept value?
Park 1
correct
incorrect
Park 3
correct
incorrect
Park 5
correct
incorrect
Park 7
correct
incorrect
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not completed
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What is the most parsimonious account of the frogspawn data?
Within each individual park there is no relationship between pond size and spawn count, but differences between parks produce an apparent effect
correct
incorrect
Some parks exhibit a negative relationship between pond size and spawn count, and this disrupts the overall positive relationship
correct
incorrect
Within each park, pond size predicts the amount of spawn, but there are substantial differences in spawn count between parks
correct
incorrect
There is no true relationship between pond size and spawn count
correct
incorrect
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