PYC3704 EXAM PREPARATION. PAST EXAM QUESTIONS.

PYC3704 EXAM PREPARATION. PAST EXAM QUESTIONS. PYC3704 - Psychological Research. Psychology is a discipline that endeavours to collect information and develop theories about human behaviour and mental processes. The aim is to establish facts that are related to psychological phenomena, that are valid and can be justified on scientific grounds. The act of simply observing phenomena and describing them or collecting facts about them is usually not sufficient. The next step in the scientific process is to go beyond the level of description by attempting to develop explanations for the things we observe: we want to know not only what the facts are, but also why they appear to be as they are. In other words, we want to develop theories, which explain why things are as they appear to be when we observe them. Psychologists try to develop explanations for human experiences and behaviour. To do this, they often have to make use of abstract concepts (also called constructs) that serve as explanations for the behaviour they observe. Psychologists are interested to find out which constructs are important (in the sense of being required or useful to explain human behaviour) and how they work together in a pattern, or what their interrelationships are. One of the objectives of psychology is not only to describe human behaviour, but also to find explanations for it. Constructs and how they interact fill the role of explanatory mechanisms in psychology. We try to find out which constructs offer an appropriate explanation of the behaviour or events we perceive, and what the pattern of their interactions with other constructs may be. In this sense, it can be said that constructs are the building blocks of theory. The link between observing a construct and measuring it is so close that when we talk about 'observation' in quantitative research, we often imply the process of measurement. The taking of a measurement is regarded as an act of observation. Research in psychology is primarily about testing theories of human behaviour. The main purpose of psychological research is to test theories empirically. # Question Ans Page Comments 4 Operationalising a construct means to ______ 1. find an explanation for the construct to explain why it appears as it is 2. make an educated guess on how it relates to other constructs 3. determine the correct level at which it should be measured 4. devise a systematic procedure to make the construct observable, in such a way that we can measure it 4 P25 'Operationalisation' is where you make the construct (which is usually an abstract concept, so it is difficult to observe it clearly) visible by finding some suitable way to measure it. You need it to be able to test a hypothesis, but it is not in itself 'the process of forming an hypothesis'. The primary aim of operationalisation is to describe a construct clearly and unambiguously so that it can be measured and tested in a research study. 5 Empirical knowledge is knowledge that is based on ______ 1. careful reasoning 2. appropriate theories 3. the observation of events 4. published research 3 P2 All scientific knowledge begins with description of the phenomena being studied, based on careful observation. Knowledge based on observation of physical events is referred to as empirical knowledge (as distinct from knowledge based on contemplation, unexplained insights, mystical experiences or claims by authority figures). # Question Ans Page Comments Use the following extract from a research proposal to answer Questions 6 to 8 “Generalised anxiety disorder (GAD) refers to a pattern of almost constant worry or tension, even when there is little or no apparent cause. Both genetic predisposition and stressors in the life of a particular patient is believed to contribute to this condition. The research will investigate whether the level of anxiety of persons diagnosed with GAD is actually reduced by psychotherapy. It is expected that patients receiving therapy will score lower on the Manifest Anxiety Scale than patients not receiving therapy " 6 “Both genetic predisposition and stressors in the life of a particular patient is believed to contribute to this condition' is ______ 1. the research hypothesis 2. a theory about the causes of GAD 3. a postulated relation between two constructs 4. a description of the constructs in terms of which GAD can be observed 2 P4 P15 P18-19 P21-26 A theory is a well-established principle that has been developed to explain some aspect of the natural world. A theory arises from repeated observation and testing and incorporates facts, laws, predictions, and tested hypotheses that are widely accepted. In science, a theory is a framework for facts. It is some kind of description that tells you how the facts are connected, and why the facts are as they are (where the word 'facts' refers to things or events that were observed and described in a careful way). A theory is a network of relations among facts that were proposed to be true and explanations for observed phenomena in terms of constructs. Constructs and their interrelations (how they affect each other, their patterns of interaction) are used in this way to develop theoretical explanations of why people behave in certain ways in certain contexts, or why mental phenomena appear to be as they are. A hypothesis is a specific, testable prediction about what you expect to happen in your study. A hypothesis can be informally described as an educated guess. As we indicated above, research usually tries to establish relationships among constructs in order to develop a theory or to test an existing theory. Usually, the theory makes it possible for us to make some kind of prediction of how constructs should be interrelated. We formulate this relationship as an hypothesis, and we test the hypothesis (using statistical methods) to see if the prediction is true. If it is not true, there is something wrong with the theory, and we need to reconsider it. # Question Ans Page Comments 7 "Whether the level of anxiety of persons diagnosed with GAD is actually reduced by psychotherapy" describes ______ 1. an observed relation between two variables 2. a theoretical prediction about the effect of psychotherapy 3. the operationalisation of the construct 'anxiety’ 4. the hypothesis to be investigated 4 P4 P15 P18-19 P21-26 See comments above 8 The dependent variable is ______ and the independent variable is ______ 1. whether or not psychotherapy is received, the level of anxiety experienced by patients 2. the effectiveness of psychotherapy, the level of anxiety 3. the level of anxiety experienced by patients, whether or not psychotherapy is received 4. the anxiety score as measured on the Manifest Anxiety Scale, the presence of stressors in the life of the patient 3 P8-9 P24 The dependent variable is the one that is predicted or explained, and the independent variable is manipulated to see how it affects the dependent variable. The independent variable is that variable which affects the dependent variable; or, conversely, the dependent variable depends on the independent variable. When a researcher focuses on the interaction of only two variables at a time, the dependent variable is usually the one that the researcher is interested in, the variable that is the focus of the research. The independent variable is something that the researcher manipulates, to see how this affects the dependent variable (in other words, the dependent variable is dependent on the independent variable). Hidden variables are effects on the dependent variable that we may be unaware of, or that we choose to ignore. Very often the events or behaviour that we observed are the consequence of many interacting factors, and we have to analyse the situation carefully to try and identify as many things as possible that may interfere with our ability to find a clear relationship between a dependent variable and some specific independent variable. One of these hidden effects that researchers in psychology often have to contend with is that people change their behaviour when they realise that someone is paying extra attention to them (usually referred to as the 'Hawthorne effect'). # Question Ans Page Comments 9 “The mental age of child number one is eight years'. In this statement 'mental age" is a(n) ______, whereas “eight years' is a(n) ______ 1. variable, specific value of that variable 2. construct, variable 3. independent variable, dependant variable 4. hidden variable, descriptive statistic 2 P7 A construct that has been measured in some way produces a variable. A variable refers to a number that can take on any one of a range of possible values. They can be discrete (when only whole numbers like 1, 2, 3 are allowed) or continuous (what mathematicians refer to as 'real numbers'). In some cases variables also take on values smaller than zero to produce negative numbers. So the (visible) variable reflects the intensity of the underlying (invisible) construct, in terms of how it was measured. We say that the variable is manifest (it is visible in the sense that we can observe it) and the construct is latent (it is invisible in the sense that we need some way to make it appear). So the latent construct is made manifest by the use of an appropriate measurement procedure. The dependent variable is the one that is predicted or explained, and the independent variable is manipulated to see how it affects the dependent variable. 10 A researcher would use a ______ to make a(n) ______ about the nature of the ______ 1. sample, inference, population 2. sample, hypothesis, population 3. variable, prediction, construct 4. population, inference, sample 1 P11 The entire collection of cases that you are interested in when you make your measurements for a particular construct is referred to as the population. The population depends on which people or objects or events you are interested in studying. Because populations can be very large, and we rarely have access to them, we would draw a sample of observations from the population and use that sample to infer certain things about the population's characteristics. The most appropriate sample is usually a simple random sample, where each individual has the same chance of being included. If our samples are not random, they may lack external validity: it may not be possible to generalise beyond the group from which we drew the sample. 11 A measurement that summarises an aspect of a population is called a ______ while a measurement that describes the same aspect of a sample is called ______ 1. construct, variable 2. parameter, statistic 3. statistic, parameter 4. variable, construct 2 P14 P23 A statistic is a sample measurement characteristic. A test statistic is the quantity you calculate (often by making use of sample statistics) to test a statistical hypothesis. When we refer to these test quantities, we always refer to the name in full - 'test statistic', and when we use the term 'statistic' on its own it refers to a descriptive statistic that describes an aspect of the sample data. Parameters are values that summarise aspects of population data While the word 'parameters' does refer to descriptive statistics, it does not refer to all descriptive statistics. It is used only for those descriptive statistics that relate to the population, not to those that describe aspects of the sample. # Question Ans Page Comments 12 A ______ is a speculative statement about the relationship among ______, based on observations or expectations 1. theory, constructs 2. hypothesis, statistics 3. theory, variables 4. hypothesis, constructs 4 P1 P18-19 A research hypothesis is formed as a clear statement in terms of a relationship among the constructs (and the variables by which they are measured). It is a statement about a possible relationship among constructs that may explain some set of observations that one intends to investigate. Constructs: concepts that act as explanations for phenomena, events and behaviour and are abstracted from observations. Theories: a theory is a frame of reference for facts that attempts to account for why things are as they are; a claim about how constructs are related to produce phenomena, which has been validated by research. 13 A class of 10 boys and 11 girls, including Mary and her friend Elizabeth, chooses a class representative by writing their names on slips of paper, putting these into a box and asking their teacher to draw one name blindly. What is the probability that either Mary or Elizabeth will be selected? 1. 1/11 2. 1/21 3. 2/21 4. 2/11 3 P29 Number of possible outcomes = Total kids = 21 Number of favourable events = Either Mary or Elizabeth = 2 p(E) = Number of favourable events Number of possible outcomes = 2 21 = 2/21 14 A college student claims that she can identify three different types of cheese by taste. An experiment is set up to test her ability. She is blindfolded and given three pieces of cheese, each representing a different brand. What is the probability that she will correctly identify TWO particular pieces of cheese by chance? 1. 0.11 2. 0.16 3. 0.33 4. 0.67 2 P35-36 The multiplicative rule states that p(A and B) = p(A) x p(B) where A and B are both independent events. This rule is used to determine the product of two or more probabilities and is indicated by the word 'and' (i.e. the probability of A and B). To identify 2 cheeses require two favourable events and therefore two calculations under multiplicative rule. First she needs to identify 1 correct cheese from 3 different types, then she needs to identify the 2nd correct cheese from the remaining 2 types. p(E) = Number of favourable events x Number of favourable events Number of possible outcomes Number of possible outcomes = 1 x 1 = 1 = 0.167 3 2 6 # Question Ans Page Comments 15 Which statement best represents an application of the law of large numbers? If I flip a coin 1000 times, it will fall heads-up ______ 500 times 1. approximately 2. exactly 3. at least 4. either much more or much less than 1 P31-32 The principle is called the law of large numbers, and it states the following: If an experiment is done repeatedly, and if the outcomes are independent of one another, the observed proportion of favourable occurrences of an event will eventually approach its theoretical probability. What the law states is that a probability value should be seen as a theoretical limit on which the relative occurrence of an event (outcome) can be expected to converge over time in the long run. For example, in the above coin-flipping example, the probability of the coin coming up heads or tails on any flip is not influenced by the result of the previous flip. Each flip is independent of the other, and the theoretical probability of heads coming up remains the same, that is, p(heads) = 1/2 = 0.5. In terms of the law of large numbers, we can make the following prediction: If we flip the coin repeatedly, even though we do not know whether heads or tails will come up on any particular flip, the actual proportion of heads will eventually get close to 0.5. Thus, as the experiment gets repeated over and over, the relative frequency or proportion of heads will approximate the theoretical probability of 0.5 16 The expression "0.05 p ≤ 0.10" should be interpreted as a probability value ______ 1. smaller than 0.05 and larger or equal to 0.10 2. halfway between 0.05 and 0.10 3. larger than 0.05 and smaller or equal to 0.10 4. smaller than 0.05 and equal to 0.10 3 P33-34 Because probabilities fall in a range from 0.0 to 1.0 when expressed decimally, a probability can never be higher than 1 or lower than 0. The general rule is written symbolically as follows: 0 ≤ p ≤ 1. Note that a probability can be 0, but to say that a probability is 0 is actually the same as saying that the event is impossible and can never happen. Likewise, to say that the probability of an event is 1 is to assert that it is an absolute certainty. In actual practice, probabilities fall within these two extremes. You will typically encounter reference to probabilities in expressions such as ''p 0.05''. This statement is interpreted as ''the probability value is higher than 0.05''. 17 Suppose that over the years 10 000 students wrote the examinations in PYC 3704-C and that 6000 of them passed, of which 300 obtained exactly 50%. This means that for randomly selected students the probability of obtaining exactly 50% is ______ while the probability of obtaining 50% or more is ______ 1. 0.60, 0.03 2. 0.05, 0.60 3. 0.60, 0.03 4. 0.03, 0.60 4 P35-36 Part 1: p(E) = Number of favourable events = 300 = 3 = 0.03 Number of possible outcomes Part 2: p(E) = Number of favourable events = 6000 = 6 = 0.6 Number of possible outcomes 10000 10 # Question Ans Page Comments 18 During the interpretation of psychological measurements the normal distribution is often ______ 1. adapted to fit the observed frequency distribution of scores 2. used as a theoretical model for interpreting the observed distribution of scores 3. used to calculate the relative frequency of observed scores 4. used to derive the mean and standard deviation of a sample 2 P50-51 Many of the scores that we use are also clustered around the average, and tail off to the ends of the distribution. Because it can be used to describe the distribution of many naturally or 'normally' occurring continuous variables, this type of symmetrical probability distribution is called a normal distribution. It is also commonly referred to as the normal curve, because the distribution can be plotted by a bell-shaped curve. The definition of the standard normal distribution (see section 2.3.3 on p52-53) is that it has a mean (μ) of 0 and a standard deviation (σ) of 1. 19 The scale along the x-axis of the standard normal distribution indicates ______ 1. probabilities 2. the mean of the distribution 3. the number of standard deviations below and above the mean 4. the p-values 3 P52-53 Statisticians have derived a rather complicated-looking equation (or formula) which describes the normal curve, and have shown that it contains only two variables, the mean (m) and the standard deviation (s), with the rest of its terms being constants. The formula produces distributions that are all bellshaped, but the actual shape of the curve - how high it is or how spread out it is - depends only on the mean and the standard deviation of the distribution concerned. 20 The mean and standard deviation of a set of test scores are 20 and 8 respectively. What is the z-score corresponding to a test score of 14? 1. 1.33 2. 0.75 3. -0.75 4. -1.33 3 P55 X - μ 14 - 20 -6 Z = σ = 8 = 8 = -0.75 Where: x represents the variable (test score), μ is the population mean, σ the standard deviation of the population from which x was obtained. # Question Ans Page Comments 21 Suppose the height of military recruits is distributed normally with a mean of 1750 mm and a standard deviation of 50 mm. Drawing repeated samples of 25 recruits each, we expect the standard deviation of the sample means to be about ______ mm 1. 2 2. 10 3. 50 4. 25 2 P61-62 P109 The standard error is an extremely valuable measure because we can use it to estimate how well a sample mean approximates its population mean in general, that is, how much error you can expect on average between the sample mean () that you calculated from your sample and the population mean (μ) that you are trying to estimate. In other words, it is an indication of the size of the error that you make by using a sample of a particular size (n) to determine the population mean. This amount of error will decrease as the size of the sample increases. σ = σ/√n = 50/√25 = 50/5 = 10 22 Which of the following statements about population parameters is the most accurate? 1. They are essential for making statements about probability distributions 2. They are always unknown but appropriate values can be estimated prior to sampling 3. They are essential, but cannot be estimated from sample information 4. They are always required prior to sampling because they are needed to calculate the sample statistics 4 P23 P13 P65 Q10 P60 Parameters are values that summarise aspects of population data While the word 'parameters' does refer to descriptive statistics, it does not refer to all descriptive statistics. It is used only for those descriptive statistics that relate to the population, not to those that describe aspects of the sample. Population parameters are rarely known (usually unknown), since the only way to determine them would be to collect the relevant data from the entire population. Population parameters are usually unknown and have to be inferred from sample data. Since population parameters are unknown, they cannot be essential to make statements about probability. Option 1 is, therefore, incorrect. Option 3 is also incorrect because it incorrectly states that population parameters cannot be estimated from sampling information, but the whole process of statistical inference is actually concerned with inferring information about a population from sample data. We use the sample to represent the population, and do our calculations on the sample data, but ultimately we want to determine the situation in the population. To do this, we often have to estimate the (population) parameters by using the (sample) statistics. A researcher seldom knows the values of the population parameters, but the values of sample statistics can be calculated by means of clearly formulated mathematical procedures and these can be used as estimates of the parameters of the corresponding population. Normally, we'll not know what our true population parameter is, and we would have calculated the mean from only a single sample - but we can still apply the basic principle: that our sample mean will be a reliable estimate of our population mean. # Question Ans Page Comments 23 What is the principal advantage of z scores? They enable one to ______ 1. determine whether scores are normally distributed around the mean 2. transform a person's scores on tests with different means and the same standard deviations into comparable percentages 3. compare a person's scores on tests with different means and standard deviations 4. determine frequency distributions for tests with different means 3 P53 P55 This curve has a mean of µ = 0 and a standard deviation of σ = 1 and is known as the standard normal distribution, and is by convention indicated with the letter 'z' (so it is also referred to as the z-distribution). The measures on this distribution are referred to as standard scores or z-scores. FIGURE 2.7: The standard normal distribution While its major use is in calculating probabilities, transforming a score from a normal distribution to its associated z-score has an additional benefit. Transforming a set of measurements, each with a different mean and a different standard deviation, into a z-score can be used to compare an individual across different distributions. After transformation, all the scores will fall on a common standard normal distribution with a mean of 0 and a standard deviation of 1, which makes it possible to compare them directly. Theorem 1 The 68-95-99.7 Rule: In every normal distribution with mean µ and standard deviation σ, approximately 68% of the data falls within one standard deviation of the mean. Approximately 95% of the data falls within two standard deviations of the mean. And finally, approximately 99.7% (almost everything) of the data falls within three standard deviations of the mean. According to the standard normal distribution tabel (z-tabel), if z=1 then the mean to z = 0.3413. Multiply by 2 to get both sides of the mean = 0.6826 or 68.26% # Question Ans Page Comments 24 Consider the following Table Subject Student X Mean of class Std. dev. of class A 50% 40% 5% B 55% 50% 5% C 60% 50% 10% D 65% 65% 5% In which subject did Student X do best, relative to his class? 1. A 2. C 3. D 4. B 1 Tut201 2012 Q21 The marks should first be converted to z-values, to make it possible to compare them across the different means and standard deviations: _ _ Z = X – X or Z= (X - X) / S S ZSubjectA = (50 - 40) / 5 = 10/5 = 2 ZSubjectB = (55 - 50) / 5 = 5/5 = 1 ZSubjectC = (60 - 50) / 5 = 10/10 = 1 ZSubjectD = (65 - 65) / 5 = 0/5 = 0 So it is clear that in the case of subject A, the student’s marks are 2 standard deviations above the mean. In the other subjects the student’s marks are 1 standard deviation or less above the mean. 25 Study the histogram below of the exam marks of a group of students in the same class. Note that the values on the horizontal axis are the class (category) limits Assume we use this histogram as a basis for making probability predictions. What is the probability that a student's score will be between 40 and 60? 1. 0.20 2. 0.10 3. 0.70 4. 0.30 2 P29 Possible outcomes = 10 + 20 + 40 + 10 + 20 = 100 Favourable events = score 40 and 60 = Exam mark of 50 with frequency = 10 = 10 P(score 40) = Number of favourable events / Number of possible outcomes = 10 / 100 = 0.10 OR Possible outcomes = 10 + 20 + 40 + 10 + 20 = 100 Favourable events = score 40 = Exammark 50,freq 10 and exammark 60, freq 20 = 10 + 20 = 30 P(score 40) = Number of favourable events / Number of possible outcomes = (10 + 20) / 100 = 30 /100 = 0.30 # Question Ans Page Comments Use the scenario below to answer Questions 26 to 31 A researcher suspects that the addition of certain food supplements to the diet of elderly people will reduce the decline in cognitive functioning that comes about because of aging. She decides to test this using a neuropsychological test that measures the speeds with which objects are identified (the Neuropsychological Perceptual Speed or NPS test). It is known that the distribution of scores on this test is approximately normal and that a mean of µ = 80 and σ = 20 was found in the population of persons older than 65. To investigate her hypothesis, she obtains a random sample of n=100 persons older than 65. Each member of this sample is given a daily dose of supplements over a period of six months. At the end of this time, each person is tested on the NPS test and a mean of ẋ = 76 is found. The researcher plans to test the hypothesis at α = 0.05. 26 The appropriate research hypothesis suggested by the scenario above is as follows 1. Cognitive functioning declines with age 2. The cognitive functioning of elderly persons is related to their perceptual speed 3. Cognitive functioning will be better for elderly persons who take the dietary supplement than for those who do not 4. The perceptual speed of elderly persons who take the dietary supplement will be greater than for those who do not 3 Tut201 2012 Q8 A psychological hypothesis formulates a testable empirical claim (something that can in principle be observed), and this usually involves postulating a relationship between two or more variables. 27 The appropriate alternative hypothesis to be tested is______ 1. H1: μ ˂ 80 2. H1: μ ˂ 84 3. H1:  ˃ 80 4. H1: μ ≠ 80 1 H0: μ = 80 which is the score of the NPS on a normal population mean. For the speed of the NPS to improve, the NPS score must go down. See this as the time it took. The alternative hypothesis will therefore be to see if the NPS gets less than 80. So H1: μ ˂ 80 # Question Ans Page Comments 28 The mean of the sampling distribution of the mean is ______ 1. 80 2. 76 3. 20 4. unknown 1 SG P60- 61 The sampling distribution of means refers to the distribution of the means of all possible samples of a particular size randomly selected from the same population μ = μ = 80 29 The standard error is ______ 1. 20 2. 2 3. 0.05 4. unknown 2 SG P60 SG P61 We can estimate the size of the error we would make if we used the sample mean as an estimate of the population mean. This is referred to as the standard error, and it is specified in the central limit theorem. The standard error is denoted by σẋ. The σ indicates that we are describing a population, and the subscript ẋ informs us that we are dealing with a population of sample means. The standard error is given by dividing the population standard deviation by the square root of the sample size σẋ = σ / √n If σ = 20 and n = 100, then σẋ = 20 / √100 = 20 / 10 = 2 30 With the information as given in the scenario, what would be the appropriate statistical test to test hypothesis? 1. A one sample t-test 2. A two sample t-test 3. A test of correlation r for relationship between variables 4. A one sample z-test 4 P100-106 The t-distribution is a statistical distribution with a probability distribution that can be determined, which means that we can use it to predict the chances of obtaining specific outcomes when testing for comparisons of means when the population standard deviation σ is unknown. So we have to use the t-test (t) when the population standard deviation (σ) is considered to be unknown - because the given standard deviation comes from the sample.