Concept explainers
Naughty or Nice? An experiment was conducted in which 16 ten-month-old babies were asked to watch a climber character attempt to ascend a hill. On two occasions, the baby witnesses the character fail to make the climb. On the third attempt, the baby witnesses either a helper toy push the character up the hill, or a hinderer toy preventing the character from making the ascent. The helper and hinderer toys were shown to each baby in a random fashion for a fixed amount of time. In Problem 39 from Section 10.2, we learned that, after watching both the helper and hinderer toy in action, 14 of 16 ten-month-old babies preferred to play with the helper toy when given a choice as to which toy to play with. A second part of this experiment showed the climber approach the helper toy, which is not a surprising action, and then alternatively the climber approached the hinderer toy, which is a surprising action. The amount of time the ten-month-old watched the event was recorded. The
Source: J. Kiley Hamlin et al., “Social Evaluation by Preverbal Infants,” Nature, Nov. 2007.
- a. State the null and alternative hypothesis to determine if babies tend to look at the hinderer toy longer than the helper toy.
- b. Assuming the differences are
normally distributed with no outliers, test if the difference in the amount of time the baby will watch the hinderer toy versus the helper toy is greater than 0 at the 0.05 level of significance. - c. What do you think the results of this experiment imply about 10-month-olds’ ability to assess surprising behavior?
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Fundamentals of Statistics (5th Edition)
- Student researchers at Hope College conducted an experiment to determine whether students memorize material better if they are taking notes on paper using handwriting as opposed to taking notes on a computer. They randomly assigned 20 students to the paper-based note-taking group and 20 students to the computer-based note-taking group. They showed all their subjects a 12-minute video about the sun and they were allowed to take notes in the method they were assigned. After the video was over, the notes were collected, and the students were given a 10-question quiz over information about the sun given in the video. Do students tend to memorize better using hand-written notes? (The results data are in the file NoteTaking.)arrow_forwardStudent researchers at Hope College conducted an experiment to determine whether students memorize material better if they are taking notes on paper using handwriting as opposed to taking notes on a computer. They randomly assigned 20 students to the paper-based note-taking group and 20 students to the computer-based note-taking group. They showed all their subjects a 12-minute video about the sun and they were allowed to take notes in the method they were assigned. After the video was over, the notes were collected, and the students were given a 10-question quiz over information about the sun given in the video. Do students tend to memorize better using hand-written notes? (The results data are in the file NoteTaking picture)arrow_forwardA researcher wanted to study the tendency of our choices to be influenced by our environment, so she conducted an experiment. The researcher recruited 90 volunteers. She randomly assigned 30 to sit in a room with red walls, 30 to sit in a room with yellow walls, and 30 to sit in a room with orange walls. After sitting in the room doing mundane activities, she offered them all a snack of strawberries, bananas, or oranges. For each individual, she recorded which room the participant was in and which snack they chose. The data are displayed in the table. The researcher would like to know if these data provide convincing evidence that the distribution of snack choice differs for the various room colors in the population of all volunteers like these. What is the appropriate inference procedure?arrow_forward
- One game at a carnival is called “Duck Pond.” This game consists of a large number of ducks that arefloating through an oval-shaped trough. A sign claims that 20% of the ducks have a blue dot on thebottom of them, 20% have a red dot, 20% have a green dot, 20% have a yellow dot, and 20% have anorange dot. Players pay to select one duck, show the color to the game attendant, replace the duck, spinaround once, and then select a second duck. If the dot on the bottom of the second duck matches the dotthat was on the bottom of the first duck, the player wins. Otherwise, the player loses. a) Are the events “color of the first duck” and “color of the second duck” independent? Explain. b) You want to perform a simulation to estimate the probability of winning this game, assuming theduck colors are distributed as claimed. Describe how you could use a table of random digits tocarry out this simulation without needing to skip any digits. c) Perform 10 trials of the simulation described in part (b)…arrow_forwardMany animals, including humans, tend to avoid direct eye contact and even patterns that look like eyes. Some insects, including moths, have evolved eye-spot patterns on their wings to help ward off predators. Scaife (1976) reports a study examining how eye-spot patterns affect the behavior of birds. In the study, the birds were tested in a box with two chambers and were free to move from one chamber to another. In one chamber, two large eye-spots were painted on one wall. The other chamber had plain walls. The researcher recorded the amount of time each bird spent in the plain chamber during a 60-minute session. Suppose the study produced a mean of M=34.5 minutes on the plain chamber with SS=210 for a sample of n=15 birds. (Note: If the eye spots have no effect, then the birds should spend an average of ?=30minutes in each chamber.) a. Is this sample sufficient to conclude that the eye-spots have a significant influence on the birds' behavior? Use a two-tailed test with ?=.05. b.…arrow_forwardMany animals, including humans, tend to avoid direct eye contact and even patterns that look like eyes. Some insects, including moths, have evolved eye-spot patterns on their wings to help ward off predators. Scaife (1976) reports a study examining how eye-spot patterns affect the behavior of birds. In the study, the birds were tested in a box with two chambers and were free to move from one chamber to another. In one chamber, two large eye-spots were painted on one wall. The other chamber had plain walls. The researcher recorded the amount of time each bird spent in the plain chamber during a 60-minute session. Suppose the study produced a mean of M=37minutes in the plain chamber with SS=288 for a sample of n=9 birds. (Note: If the eye-spots have no effect, then the birds should spend an average of μ=30 minutes in each chamber.) Is this sample sufficient to conclude that the eye-spots have a significant influence on the birds’ behavior? Use a two-tailed test with a= .05. Compute the…arrow_forward
- Many animals, including humans, tend to avoid direct eye contact and even patterns that look like eyes. Some insects, including moths, have evolved eye-spot patterns on their wings to help ward off predators. Scaife (1976) reports a study examining how eye-spot patterns affect the behavior of birds. In the study, the birds were tested in a box with two chambers and were free to move from one chamber to another. In one chamber, two large eye-spots were painted on one wall. The other chamber had plain walls. The researcher recorded the amount of time each bird spent in the plain chamber during a 60-minute session. Suppose the study produced a mean of M = 34.5 minutes on the plain chamber with SS = 210 for a sample of n = 15 birds. (Note: If the eye spots have no effect, then the birds should spend an average of μ = 30 minutes in each chamber.) a. Is this sample sufficient to conclude that the eyespots have a significant influence on the birds’ behavior? Use a two-tailed test with α =…arrow_forwardIn an experiment, 1919 babies were asked to watch a climber attempt to ascend a hill. On two occasions, the baby witnesses the climber fail to make the climb. Then, the baby witnesses either a helper toy push the climber up the hill, or a hinderer toy preventing the climber from making the ascent. The toys were shown to each baby in a random fashion. A second part of this experiment showed the climber approach the helper toy, which is not a surprising action, and then the climber approached the hinderer toy, which is a surprising action. The amount of time the baby watched the event was recorded. The mean difference in time spent watching the climber approach the hinderer toy versus watching the climber approach the helper toy was 105 seconds with a standard deviation of 195 seconds. State the null and alternative hypotheses to determine if babies tend to look at the hinderer toy longer than the helper toy. Let μd=μhinderer−μhelper,μd=μhinderer−μhelper, where μhinderer is the…arrow_forwardMany animals, including humans, tend to avoid direct eye contact and even patterns that look like eyes. Some insects, including moths, have evolved eye-spot patterns on their wings to help ward off predators. Scaife (1976) reports a study examining how eye-spot patterns affect the behavior of birds. In the study, the birds were tested in a box with two chambers and were free to move from one chamber to another. In one chamber, two large eye-spots were painted on one wall. The other chamber had plain walls. The researcher recorded the amount of time each bird spent in the plain chamber during a 60-minute session. Suppose the study produced a mean of M = 37 minutes in the plain chamber with SS = 288 for a sample of n = 9 birds. (Note: If the eye-spots have no effect, then the birds should spend an average of μ = 30 minutes in each chamber.) Is this sample sufficient to conclude that the eyespots have a significant influence on the birds’ behavior? Use a two-tailed test with α = .05.…arrow_forward
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