Question:In this assignment we analyze data that was collected as part of an experiment that investigated the mental relation between weapon and aggression. The experiment involved 32 undergraduate students ranging in age between 18 and 24 years. They were told that the purpose of this study was to test reading ability of various words. Each student was exposed to 192 trials. In each trial a computer presented a priming stimulus word for 1.25 seconds, a blank screen for 0.5 seconds, and then a target word. The experimenter instructed the subjects to read the first word to themselves and then to read the second word out loud as quickly as they could. The computer recorded reaction times.

The 192 trials were divided into 4 groups of size 48 each. In one group the priming stimulus word was a weapon word (such as "dagger" or "bullet") and the target word was an aggressive word (such as "destroy" or "wound"). In another group the target word was instead a nonaggressive word (such as "evacuate" or "ashamed"). The third and fourth groups involved a name of an animal (such as "rabbit" or "dog") as the priming stimulus word and the target, again, was either an aggressive or a nonaggressive word.

The file "weapons.csv" contains, for each subject and for each group of trials, the average of the 48 reaction times. The file can be foundhere. The file contains 5 variables:

• sex= The sex of the subject.
• aw= Aggressive target word following a weapon prime.
• an= Aggressive target word following a nonweapon (animal) prime.
• cw= Control target word (nonaggressive) following a weapon prime.
• cn= Control target word (nonaggressive) following a nonweapon prime.

(This data set is taken from theRice Virtual Lab in Statistics. More details on this experiment can be found in the case studyWeapons and Aggressionthat quotes as a source the paper: Anderson, C.A., Benjamin, A.J., & Bartholow, B.D. (1998). Does the gun pull the trigger? Automatic priming effects of weapon pictures and weapon names. Psychological Science, 9, 308-314.)

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Mark all the variables of type "factor":

Select one or more:

a. sex

b. aw

c. an

d. cw

e. cn

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The total number of missing values is:

Answer:

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Mark all the null hypotheses that arenot rejectedwith a significance level of 5%:

Select one or more:

a. The expected value of "an" is the same both for males and for females.

b. The expected value of "aw" is the same both for males and for females.

c. The expected value of "cn" is the same both for males and for females.

d. The expected value of "cw" is the same both for males and for females.

e. All of the given null hypotheses are rejected.

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Mark all the null hypotheses that arenot rejectedwith a significance level of 5%:

Select one or more:

a. The variance of "an" is the same both for males and for females.

b. The variance of "aw" is the same both for males and for females.

c. The variance of "cn" is the same both for males and for females.

d. The variance of "cw" is the same both for males and for females.

e. All of the given null hypotheses are rejected.

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One may measure the effect of a "weapon" primer on the speed in naming a word associated with aggression by considering the difference "aw - an". Call this difference "da". Likewise, one may measure the effect of a "weapon" primer on the speed in naming a neutral word by considering the difference "cw - cn". Call this other difference "dc". An overall contrast that may be used in order to test the relation between a "weapon" primer and a target associated with aggression is the difference "da - dc". Apply the t-test in test the null hypothesis that the expectation of the contrast is zero against a two-sided alternative. The resulting p-value is: (Give an answer of the form x.xxx, i.e. with 3 significance digits)

Answer:

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Construct a 95%-confidence for "aw - an" and a 95%-confidence interval for "cw - cn". The value 0 is contained in:

Select one:

a. Only in the confidence interval for "aw - an".

b. Only in the confidence interval for "cw - cn".

c. Both confidence intervals.

d. Neither of the confidence intervals.

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The variable "aw" is the reaction time for a target word associated with aggression when the primer is a word associated with weapons. The variability of this variable between the subjects may be attributed in part to variability in reading ability among people. One may propose the variable "an" as measure of reading ability of words associated with aggression when the "weapon" effect is not present. Let "an" be an explanatory variable and let "aw" be the response. The percentage of the variance that is explained by the explanatory variable is:

Select one:

a. Less than 25%.

b. Between 25% and 50%.

c. Between 50% and 75%.

d. More than 75%.

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Consider a regression model where "an" is the explanatory variable and "aw" is the response. Consider the 95%-confidence intervals for the intercept and the slope. Then:

Select one:

a. The value 0 belongs to the confidence interval for the intercept and the value 1 belongs to the confidence interval for the slope.

b. The value 0 belongs to the confidence interval for the intercept but the value 1 does not belong to the confidence interval for the slope.

c. The value 0 does not belongs to the confidence interval for the intercept but the value 1 belong to the confidence interval for the slope.

d. The value 0 does not belong to the confidence interval for the intercept and the value 1 does not belong to the confidence interval for the slope.

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Below is the data needed to complete the assignment

sex aw an cw cn F 44.6667 44 43.2409 45.1564 F 42.7083 43.7273 46.8628 45.1278 F 41.6957 41.8182 44.4939 43.3712 F 34.7778 37.1364 35.2715 34.4035 F 47.0833 44.3478 46.2482 46.3137 F 39.7727 41.7647 42.9762 42.1587 F 44.125 44.6667 43.5898 43.6742 F 41.1667 42.2917 41.5536 39.4447 F 41.619 45.1304 41.803 43.173 F 38.7083 37.2083 38.7615 39.4606 F 38.5833 37.5417 38.22 38.214 F 38.125 38.875 38.6709 39.4718 F 42.8333 43.0417 42.7684 42.6061 F 35.7917 38.3333 36.8816 37.8219 F 33.3158 34.3125 30.0319 29.4278 M 43.7826 43.7619 43.5041 43.6543 M 49.7727 54.0952 50.7373 55.4451 M 28.5556 31.1176 28.8856 26.8333 M 33.7059 34.1765 34.6903 31.7301 M 38.6667 39.0435 37.7833 38.4417 M 41.1364 40.2609 38.3768 40.0405 M 52.9545 54.3913 54.9234 53.7414 M 44.125 42.6364 43.0367 42.6009 M 44.125 42.6364 43.0367 42.6009 M 44.625 42.7727 44.5337 43.3814 M 39.8261 41.875 42.2875 42.6104 M 40.2174 41.125 42.7546 42.9607 M 30.1176 34.4118 33.6941 31.9481 M 43.25 42.625 44.6222 44.6203 M 47.9048 49.1739 49.8551 49.8009 M 39.1304 38.0833 39.9209 39.7252 M 42.5217 46.0833 42.6268 42.7801