Chapter 2.pdf

Chapter 2: Overview What is a science? How do psychologists conduct research? How do psychologists make sense of research results? © Dr. Anneke Olthof 2024  What is a Science? Basic assumption – events are governed by some lawful order that can be observe...

Chapter 2: Overview What is a science? How do psychologists conduct research? How do psychologists make sense of research results? © Dr. Anneke Olthof 2024  What is a Science? Basic assumption – events are governed by some lawful order that can be observed, measured, and tested © Dr. Anneke Olthof 2024  What is a Science? The scientific method is designed to help the scientific process remain as accurate and precise as possible ✓ Psychology uses the scientific method © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 1: make observations, review the literature – Example: You’re working at camp and notice that kids who eat more sugar are less able to follow rules and instructions for the games and activities you create for them. Makes you wonder about the link between refined sugar consumption and hyperactivity, so you review previous studies – What do we already know about this??? © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 2: develop a testable hypothesis – Hypothesis = A tentative prediction about the relationship between two or more variables Variable = Any measurable condition that is controlled or observed in a study Best if the variables are operationally defined – Defined in such a way that it is testable and observable © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 2: develop a testable hypothesis – Examples: Children who consume more calories from sugar will ask more questions and make more errors during activities. Children who eat a minimum of 3 chocolate bars per day will spend more time in time-out during activities. Children who consume more than 50 mg of refined sugar in a day will be less able to sit still in a chair for 15 minutes. © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – A random sample of participants is chosen from the population Population = the entire group that is of interest to researchers Sample = the portion of the population that is used in the study – Sampling bias = choosing a sample that does NOT represent your population © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – To make conclusions about a population based on your sample, and avoid sampling bias, you need: sample = population – How??? Random sampling = making sure that every individual in the population has an equal chance of being included in your sample © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – There are three methods of data collection psychologists rely on to describe the characteristics of behaviour: Case studies Naturalistic observation Surveys and questionnaires © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – The case study: An in-depth investigation of a single participant using different data collection techniques Advantages: – Useful method to study rare behaviours – Very detailed – Can be a source of support for the cause of behaviour Disadvantages: – Results may not generalize to other people – Potential for researcher bias – when the researcher sees only what they expect to see – Cannot determine cause and effect © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Naturalistic observation: Observing and recording the participant’s natural behaviour, without influencing the participant Advantages: – Behaviour studied under natural conditions – Good to use in conjunction with lab experiments Disadvantages: – Time consuming – Difficult not to influence behaviour – Potential for Hawthorne effect – when participants act differently because they know they’re being observed – Cannot determine cause and effect © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – The survey and questionnaire: Participants are asked a series of questions about certain aspects of their behaviour (written or interview) Advantages: – Quick and cheap data collection – Good to study behaviours that cannot be directly observed Disadvantages: – Careful of wording effects – Results depend on what the participants themselves say – Potential for participant bias – when participants answer according to what they think they should say rather than truthfully – Cannot determine cause and effect © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – There are two main types of research methods that psychologists use to test their hypotheses: Focus Experimental research = research that is used to here now demonstrate cause and effect Correlational research = research that asks how variables are related to each other © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Experimental research: The researcher manipulates a variable There are different groups of participants, and each group is exposed to something different Allows cause-effect conclusions © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Experimental research definitions: Independent variable (IV) = the variable that is manipulated Dependent variable (DV) = the variable that is measured Experimental Group = the group that receives the manipulation Control Group = the group that doesn’t receive the manipulation and serves as a comparison © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Two types of groups in experimental research: Example: need to ensure that the experimental group is the same as the control group EXCEPT for the dose of sugar consumption Experimental group: Control group: Consumption of 50 mg or more Consumption of less than 20 mg of refined sugar within a 24 hour of refined sugar within a 24 hour period for 7 consecutive days period for 7 consecutive days Measure sit-still score in the Measure sit-still score in the stabilimeter chair for 15 minutes stabililmeter chair for 15 minutes © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – This is how experiments allow for cause and effect conclusions; because: If the only difference between the experimental and control group is the independent variable, then any difference found between groups must be caused by the independent variable – Example: if the only difference between our two groups of children is the amount of sugar consumption, then any difference in sit-still scores between the two groups must be caused by the sugar consumption © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – How can we be sure that our experiment contains two groups are the same in every way except for sugar consumption? – What if our groups differ in some other way??? Eg: All children in the high sugar dose group were diagnosed with ADHD and all children in the low sugar dose group had no such diagnosis – Then the experiment loses all it’s power! – Thus, it is critical that the only difference between groups is the independent variable – So, how do you do this??? © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Random assignment = when each person in your study has an equal chance of going into either of your groups Random sampling Exp.’tal ? Group Random assignment Control © Dr. Anneke Olthof 2024 Group  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Experimental research: Advantages: – Good control – Can identify cause and effect Disadvantages: – Ethical concerns – May have practical limitations – Artificial conditions © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Recall that there are two types of research methods that psychologists use to test their hypotheses: Experimental research = research that is used to demonstrate cause and effect Focus Correlational research = research that asks how here now variables are related to each other © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Correlational research: Researcher just measures two (or more) variables Uses statistics to see if the variables are related Nothing is manipulated Does NOT allow cause-effect conclusions © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Example: Do children who eat more sugar in a day score higher on a measure of hyperactivity? Measure sugar consumption and hyperactivity in each child and plot results … Sugar Consumption (mg) Child Sugar Consumption (mg) Hyperactivity Score 1 65 80 2 10 30 3 60 75 4 30 70 5 30 10 Olthof 2024 © Dr. Anneke Hyperactivity Score  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Could also find different patterns … Sugar Consumption (mg) Sugar Consumption (mg) Sugar Consumption (mg) Hyperactivity Hyperactivity Hyperactivity Score Score Score © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – The calculated statistic is called the correlation coefficient, and is symbolized by ‘r ’ A numerical representation of the relation between variables 0 -1.0 © Dr. Anneke Olthof 2024 +1.0 0  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Hypothetical ‘r’ values for our earlier hypothetical data plots Positive correlation, r =.63 No correlation, r = 0 Negative correlation, r = -.72 Sugar Consumption (mg) Sugar Consumption (mg) Sugar Consumption (mg) Hyperactivity Hyperactivity Hyperactivity Score © Dr. Anneke Score Olthof 2024 Score  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – If we find a correlation, what conclusions can we draw from it? Suppose we find that there is a positive correlation between ice cream sales and rates of violent crime – Ie, as ice cream sales increase, rates of violent crime increase – Does this mean that ice cream causes violence??? © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Correlation is NOT causation – a relationship between two variables doesn’t mean that one variable caused the other Eating ice cream causes violent behaviour Violent behaviour causes ice cream eating Both eating ice cream and violent behaviour are the result of some third variable – Hot temperatures, blood sugar levels, hunger © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Correlational research: Advantages: – Useful for studying topics that can’t be studied using experimental methods due to ethical/practical reasons – Can study behaviours under more natural conditions Disadvantage: – Does not allow causal conclusions © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 3: choose participants, select the research method, collect data – Data collection needs to be done empirically, without any biases Double-blind procedure = neither the participant nor the researcher knows who is in which group – Example: neither the children themselves, nor the person collecting data from the s sit-still chair, know who consumed sugar and who didn’t © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 4: analyze the data, accept or reject the hypothesis – Use statistics (see Appendix B and 5-Minute Psych …) – If hypothesis WAS supported: Confidence in theory increases – Theory = a set of interrelated ideas used to explain a set of observations Consider alternative explanations Inspect data and research methods for possible errors – If hypothesis WAS NOT supported: Confidence in theory decreases Revise, refine, or discard theory © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 5: seek scientific review, publish, replicate – Allows your work to be reviewed, criticized, and scrutinized by other experts in the field – Ensures that the research you read in peer-reviewed journals is top-notch © Dr. Anneke Olthof 2024  How Do Psychologists Conduct Research? Step 6: build a theory – Incorporate your results into existing theories or develop a new theory – Process starts over again at Step 1 © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Statistics! – Recall two main types of research methods: Correlational research – no manipulation, the researcher just measures two variables – The correlation coefficient indicates if there is a relationship between the two variables, represented by the statistic ‘r’ Experimental research – researcher manipulates a variable and compares performance across different groups – Inferential statistics indicate if the difference between groups is meaningful © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Correlations describe relations – What can we say about the relation between variables when we know the correlation coefficient ‘r’? Two variables are more likely to be significantly related if ‘r’ is closer to +/- 1 and if more participants were tested © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Experiments allow causal conclusions – Use inferential statistics to make inferences about data sets Conclude differences between groups are genuine and not due to chance – results are ‘significant’ To do this, first need to look at descriptive statistics – Statistics that are used to organize raw data into meaningful descriptions © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Descriptive statistics – Measures of central tendency = a numerical value that represents the center of the distribution Example: mean, median, mode – Measures of variability = a numerical value that represents how different the scores within a group are from each other Example: range, standard deviation, variance © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Descriptive statistics in our example: – Recall we were comparing sit-still scores (high numbers indicate a lot of movement in the chair) in children who ate more than 50 mg of refined sugar per day for 7 consecutive days with children who ate less than 20 mg of sugar Experimental Group Control Group (20 mg (50 mg refined sugar) refined sugar) Mean 150 50 Standard Deviation 20 5 Number of Children 100 100 © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Inferential statistics – Using the appropriate inferential test, a researcher calculates the statistical significance of their results When you have a “very low probability” that your findings are due to chance – What is considered a “very low probability”? » Researchers generally accept a 5% chance that the results are due to chance alone If so, you could say that your findings are ‘statistically significant’, and you would say that ‘p <.05’ © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? appropriate inferential test translate result into p-value Statistically Statistically non- significant significant p <.05 p >.05 © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? What is the appropriate inferential statistic? – It depends on your research design Recall our example: compared two groups of participants tested at one point in time and manipulated one independent variable – The inferential statistic used for testing the statistical significance of two groups is a t-test If the difference between the two means is great t = [diff b/w grp means] enough, and the variability within groups is small [var w/i grps] enough, then you will find a big t-value If your t-value is big, your p-value will be small © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Consider experimental variations: – Test a single group of participants at two points in time and manipulate one independent variable Week 1: Week 2: Half children eat 50 mg of Children switch groups for the sugar/day for 7 days; other half second week (ie, the 50-mg eat 20 mg of sugar/day children now eat 20-mg) Child sits in sit-still chair for 15 Child sits in sit-still chair for 15 minutes minutes Chair measures the number of Chair measures the number of movements movements Comparing two groups = t-test © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Consider experimental variations: – Test multiple groups of participants at one point in time and manipulate one independent variable Group 1: Group 2: Group 3: 50 mg of sugar/day for 25 mg of sugar/day for 0 mg of sugar/day for 7 days 7 days 7 days Child sits in sit-still Child sits in sit-still Child sits in sit-still chair for 15 minutes chair for 15 minutes chair for 15 minutes Chair measures the Chair measures the Chair measures the number of number of number of movements movements movements Comparing more than two groups = F-test © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? Consider experimental variations: – Manipulating two independent variables – Example: Sugar Consumption Does eating refined sugar 50 mg 20 mg increase hyperactivity? Does regular No Exercise cardiovascular exercise decrease Yes hyperactivity? Comparing more than two groups = F-test © Dr. Anneke Olthof 2024  How Do Psychologists Make Sense of Research Results? experimental research Comparing two Comparing more groups than two groups t-test F-test t-value F-value Statistically Statistically non- significant p-value significant p <.05 p >.05 © Dr. Anneke Olthof 2024