Psych 1315 1st Edition Lecture 2 Outline of Current Lecture I II Methods Properties of a good measure when testing individuals for observation Current Lecture 1 Properties of a good measure when testing individuals for observation a Validity what influences occur to make people smile The extent of happiness causing one to smile example used number of friends doesn t define happiness i Demand characteristics behaving a way you think you should behave when someone is watching This makes it hard to measure behavior ii Naturalistic observation when you figure out what is going on and change your behavior iii Observer bias 1 Example Doing a study to show that boys have more aggressive behavior but only focusing on the boys behavior and not noticing the girls aggressive behavior as well iv Double blinded there is no influence between the observer or participant b Reliability the tendency of a measure to produce same measurements for every same thing i Test retest reliability the likelihood that a measure s second assessment of a variable will get the same result as the first time ii Inter rater reliability having two raters use the same measure and comparing how similar they are c Power detecting concrete conditions specified in operation definition and powerless when you cannot detect differences 2 Data a Frequent distribution a graphic representation of a measurement b Central tendency i Correlation two variables that are synchronized have a relationship 1 Always write down correlation relationship ii Causation noticing a cause and effect but no relationship 1 Example the amount of people who eat ice cream is not related to the number of cases of murder although they both increased throughout the same period of time at the same rate 2 Always remember correlation DOES NOT EQUAL causation 3 Construct any complex psychological concept model or schematic idea that happens in the human brain and we cannot see but can be tested a Intelligence b Personality c Love d Motivation e Memory 4 Use construct validation to a compare measures i gather as many measurements as possible ii look for the ones that cohere or hang together iii example intelligence tells you how intelligent someone is b forms of validity i Criterion determines how good a test is by comparing it to an external standard ii Predictive does the test predict some outcome or standard in the future iii Convergent refers to whether a test correlates with other measures of the same construct iv Face does the test appear to measure what it s supposed to 5 Organizing data a Population vs sample in psychology sample is used more often than population because of the smaller numbers of participants This is more time consuming b Graphical representation it is better to make your data a visual representation to prove your study c Frequency count refers to the number of events that happen in a set period of time d Frequency distribution graphical representation of measurements arranged by the number of times each measurement was made 6 Descriptive statistics a Frequency count refers to the number of events that happen in a set period of time b Frequency distribution graphical representation of measurements arranged by the number of times each measurement was made c Central tendency i Mode value of most frequently observed measurement ii Mean average of a measurements iii Median the middle number d Variability i Range largest measurement minus the smallest measurement ii Standard deviation the average difference between the measurements in a frequency distribution and the mean of that distribution 7 Case studies a Example used in class kids were tested to see if they could wait 15 minutes without eating a marshmallow in front of them with a reward of more marshmallows if they could wait Two out of three could not wait the fifteen minutes without eating the marshmallow The same kids were tracked down to when they turned eighteen years old to see how they were doing financially and in school The results showed that the one out of three kids that were able to wait were more successful and had better grades than those who ate the marshmallow b Another study shown was where patient HM had part of the hippocampus removed from his brain and lost his memory Patient HM could not build memories or remember parts of his past This is how we came to a conclusion that the hippocampus deals with memories i Ideographic description of one vs Nomothetic statistical comparisons of groups 8 Population vs sample a Population every person in the universe within given criteria b Sample a subset of any given population c Law f numbers the larger your sample the closer it gets to representing the actual population i Why do we use samples in psychology It is more time consuming to stick to samples 9 Correlation method a Scatter plot chart on which each point represents an individual s scores on two variables b Correlation coefficient r reflects the strength and direction of relationship r always being in between 1 and 1 i Directions 1 Positive both variables increase or decrease together 2 Negative as one variable increases the other decreases ii No correlation there is no relationship between the two variables 10 Causation a Natural correlations a correlation observed in the world around us b Third variable problem the possibility of a third variable correlation when a casual relationship between two variables cannot be inferred c Third variable problem the fact that two variables are correlated only because each is casually related to a third variable 11 Experimentation a Manipulation creation of an artificial pattern of variation in a variable in order to determine its casual patterns i Independent the variable that is manipulated in an experiment ii Dependent the variable that is measured in a study b Random assignment procedure that uses random event to assign people to the experiment or control i Experimental group treated in a particular way in an experiment ii Control not treated in a particular way c Self selection a problem that occurs when anything about a person determines whether he or she will be included in the experiment or control group 12 Quality of data generalizability the degree in which a measurement or result of an experiment applies to other tests situations or people and retains its validity across various contexts 13 Ethics of science protection of participants a Informed consent freedom of coercion protection from harm risk benefit