## Exam (elaborations)

# PYC3704 - Psychological Research (2021 - Semester 1 and Semester 2 - Assignment 2)

PYC3704 – Psychological Research 2021 - Semester 1 and Semester 2 - Assignment 2 Question 1: Why do we calculate a test statistic? 1. To determine whether or not we can accept that the null hypothesis is true. 2. To determine how far the observed measurements deviate from what we may expect by chance. 3. To get a measurement by which we can calculate the level of significance. 4. To determine whether or not we can reject the alternative hypothesis. Question 2: A researcher wants to test the hypothesis that the mean depression score on a depression scale of patients diagnosed with clinical depression is greater than 120. The statistical hypothesis to be tested is: H_0: μ=120 H_1: μ>120 She uses a random sample of n = 64 drawn from the population of diagnosed patients and finds that x ̄ = 127 and s = 24. Which of the values below is the closest to the correct value of S_x ̄ ? 1. 0.37 2. 3.0 3. 0.61 4. S_x ̄ cannot be calculated from the information that was provided Question 3: Suppose the alternative hypothesis states that μ>60. The researcher should test H_0 against H_1 if the ... 1. sample mean is larger than 60 2. sample mean is smaller than 60 3. sample mean differs from 60, irrespective of the direction of the difference 4. p-value is smaller than the level of significance Question 4: When applying a t-test for the difference between the means of two independent samples. The probability of obtaining the calculated t-statistic under the null hypothesis is compared to the ... to reach a decision. 1. level of significance 2. degrees of freedom 3. two-tailed probability 4. effect size Question 5: A social psychologist wants to test how long people will wait before responding to cries of help from an unknown person. The psychologist wants to confirm this suspicion that people will take less time to react when they hear a female voice when they hear a male voice. He tests this on sample of n=15 people who are told (one at a time) to sit in a waiting room to be called for an interview. While they wait, each participant hears a call for help from a male or female voice, which is actually a recording. The dependent variable is the number of seconds that each participant waits until they go to investigate or tried to find help. The sample following sample statistics are calculated from the results: Male voice: x ̄_1=11.9 seconds; s_1=3.5 Female voice: x ̄_1=15.3 seconds; s_1=4.1 Given these findings, what type of statistical test will the psychologist have to do to confirm the relevant statistical hypothesis? 1. A one-tailed statistical test 2. A two-tailed statistical test 3. A test for independent samples Question 6: A researcher wants to test the following hypotheses: H_0: μ_1=μ_2 H_1: μ_1≠μ_2 On the basis of data provided, the output from a computer program indicated that a t-value of t = 1.72 was found, with the p-value for a two-tailed test given as p = 0.056. What should the researcher do to evaluate this result at a level of significance of = 0.5? 1. Divide the p-value by 2 before comparing it with 2. Multiply the p-value by 2 before comparing it with 3. Divide by 2 before comparing p to 4. Compare the p-value as given with Question 7: A matched pair t-test should be used when they are ... 1. testing a two-nailed hypothesis 2. comparing means on a measurement from before and after a specific event 3. comparing two variables which come from the same group 4. comparing two means on a variable where the data were drawn from the same population Question 8: Which of the symbolic expressions below are appropriate for symbolizing a population variance? 1. 2. ^2 3. s 4. s^2 Base your answers to Question 9 and 10 on the following scenario: To test the efficacy of a workshop aimed at improving people’s interpersonal skills, a researcher applies a scale which rates the interpersonal skills of 20 participants before and after they participate in the workshop. Scores on his rating scale among the general population have a mean of 5 and a standard deviation of 1.5. Question 9: 1. H_0: μ_1=5 2. H_0: μ_1=μ_2 3. H_0: Đ =0 (where Đ is the population mean of the differences scores) 4. H_1: μ_1≠μ_2 Question 10: Which is the appropriate test statistic to calculate to test the hypothesis in the previous question? 1. The z-statistic for the mean of a sample 2. The t-statistic for the difference between the means of two dependent samples. 3. The t-statistic for the difference between the means of two independent samples. 4. The t-statistic for the mean of a single sample. Question 11: In which circumstance can the z-test for comparing two independent means NOT be used? 1. The population parameters are available to a reasearcher. 2. The population standard deviations for the two groups are unknown. 3. The population means for the two groups are unknown. 4. The sample standard deviations for the two groups are unknown. Question 12: When studying correlations in research, one investigates the relation between ... 1. the mean of a single sample of subjects and a population mean 2. two dependent groups of subjects, with respect to a single variable 3. two variables measured on the same group of subjects 4. two independent groups of subjects, with respect to a single variable Question 13: A positive correlation between variables X and Y implies that persons scoring low on X will generally score ... on Y. 1. high 2. low 3. either high or low 4. in an indeterminate way Question 14: A number of psychiatric patients are classified by gender (male or female) and into one of four categories as schizophrenic, severely depressed, bipolar disorder and others. Which of the following is suitable for representing counts or frequencies of persons which fall into each possible subcategory? 1. A contingency table 2. A scatter plot 3. A histogram 4. A spreadsheet Question 15: Two samples may be regarded as independent when ... 1. there is no systematic relationship between the composition of one sample and the other they were drawn at different occasions 2. they were drawn at different occasions 3. each measurement in one sample can be matched with a measurement in the other sample 4. they are both totally random Question 16: A researcher wants to establish whether a relationship exists between people’s religious affiliation and whether they are in favour of or against the death penalty (yes or no). Which of the following would be the most appropriate test to use? 1. The t-test for two independent samples. 2. The chi-square 〖(x〗^2) test statistic. 3. Pearson’s correlation test statistic. 4. The t-test for two dependent samples. Question 17: An important aspect in the research process includes refining the research hypothesis until it suggests or implies the follow? Choose the best answer combinations to answer your question. a) Defining the research population b) Mentioning the procedures used in how the constructs will be measured. c) Assessing the validity of the constructs. d) Detailing the nature of the relationship being investigated. 1. (a) and (b) are true 2. (b) and (c) are true 3. Only (c) is true 4. (a), (b) and (d) are true Question 18: To test the efficacy of psychotherapy aimed at relieving depression, a researcher applies a depression scale to 50 depressed patients at the start and again at the end of their treatment, predicting that the latter scores will be lower (reflecting less depression). Scores on his depression scale among the general population have a mean of 30 and a standard deviation of 10. Which research design is appropriate to test the research hypothesis? 1. A two-sample groups design with independent groups. 2. A two-sample groups design with dependent groups. 3. A one-sample groups design. 4. A design where the correlation between two variables is tested. Question 19: Suppose you compare a group mean with a particular population mean by using a t-test, and you find that the t-test statistic calculated for your research results is zero. Which conclusion is appropriate? 1. The p-value will be extremely small. 2. The null hypothesis is likely to be true. 3. The alternative hypothesis is likely to be true. 4. The null hypothesis can probable be rejected. Question 20: Suppose you calculate the correlation between two variables, X and Y, and you find a very high correlation of greater than 0.9. Why cannot you infer from this that one variable is the cause of the other one? 1. The direction of the effect of the one variable on the other is not known. 2. The direction of the causation can work in both ways. 3. You first have to establish which variable is dependent on which. 4. The effect may be the consequence of hidden variables affecting both X and Y. Question 21: A contingency table is used to summarise the relationship between two variables measured on a(n) ... scale. 1. nominal 2. ordinal 3. interval 4. ratio Question 22: In a scatter diagram, the more tightly clustered the data points are around a straight line, the ... the correlation is between the two variables. 1. lower 2. higher 3. closer to zero 4. closer to 1 Question 23: A variable that can take only one of two possible values is called ... 1. binomial 2. dichotomous 3. nominal 4. categorical Question 24: Employees of a large organisation can be classified into one of three groups, technical, clerical and managerial workers. Based on a survey, these workers are divided into workers that are satisfied with their working conditions, and those that are dissatisfied. A researcher wants to determine whether there are differences between the different types of worker as far as their satisfaction is concerned. Which would be the most suitable statistical test to do? 1. The test statistic based on the correlation of the type of work with the level of satisfaction. 2. Use a t-test to determine for independent sample whether differences exist between those that are satisfied and those that are not. 3. Use the chi-square test to see if the distribution of level of satisfaction differs for the different job category. 4. Use a t-test to determine for independent sample whether differences exist between those that are satisfied and those that are not. Based your answers to Question 25 to 26 on the following scenario: James engages in a statistical hypothesises and highlights that sleep deprivation affects cognitive performance negatively. He selects a sample of 21 students randomly and deprives them of sleep for 10 hours over and above the normal 14 hours during which they are awake in a day. James them measures each student’s performance on a computer game that requires cognitive skill to play. It is known that the general population of students has a mean score of 1200 for the particular computer game, with a standard deviation of 200. Suppose it is found that the mean score for the sample is 1050. Question 25: What is the null hypothesis? 1. The mean score in the computer game of all students is 1200. 2. The mean score in the computer game of all students deprived of sleep is 1200. 3. The mean score in the computer game of 21 students deprived of sleep is 1200. 4. The mean score in the computer game of 200 students is 1200. Question 26: What is the alternative hypothesis? 1. The mean score in the computer game of all students is not equal to 1200. 2. The mean score in the computer game of the sample of students deprived of sleep is less than 200. 3. The mean score in the computer game of students deprived of sleep is less than 1200. 4. The mean score of the computer game of all students is 200. Question 27: James found that variables 1 and 2 in his hypothesis testing has no relationship with each other, which it was in fact found that there is a statistical relationship between variables 1 and 2. Choose which error this statement refers to? 1. Type II 2. Type I 3. A false error 4. A significant result Question 28: Based on the above scenario, James engaged in a ... which is a speculative statement about the relationship among ..., based on observation or expectations. 1. theory; constructs 2. hypothesis; statistics 3. theory; variables 4. hypothesis; constructs Use the following scenario to answer Question 29 and 30. Lila wonders whether a relationship exists between a person’s length and their leadership ability. She collects data from a sample of 95 people, classifying them as short or tall, and as leaders, followers and those she could not classify. From this, she creates the contingency table below. Cross-classification Tall Short Leader 12 32 Follower 22 14 Unclassifiable 9 9 Question 29: Consider the scenario given above. If frequency data is evenly distributed throughout the categories, with no proportional difference between tall and short people as far as leadership abilities go, what should the expected value of the frequency of short leaders be? (In other words, the number of people who can be classified as both ‘short’ and as ‘leaders’, if these variables have no effect on each other). 1. 15.8 2. 19.9 3. 24.08 4. 32 Question 30: Calculate the value of the appropriate test statistic which Lila would need to consider if she wants to determine whether a relationship exists between length and leadership ability. If we use ‘ Q’ to indicate the result of this calculation, which of the following statements is true? 1. Q < 0 2. 0 ≤ Q < 4 3. 4 ≤ Q < 8 4. Q ≥ 8

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