Psychology Statistics Exam #1 Questions And Answers Verified Solutions| Graded+

Descriptive Statistics - correct answers Organize, summarize and communicate a group of numerical observations. They describe large amounts of data in single numbers or a few numbers. This communicates the message more clearly than a whole list (of weights) ex. The number of pounds an average woman weighed in 1960's vs. 2010. They describe the weights of many people in one number (mean, median, mode) Inferential Statistics - correct answers Use sample data to make general estimates about the larger population. They infer or make intelligent guesses about the larger population. ex. CDC made an intelligent guess about the average weight of the population based on a smaller representative group of US citizens to make an intelligent guess about the entire population Sample population - correct answers A set of observations drawn from the population of interest. It includes all possible observations about which we'd like to know. Researchers study a sample but are really interested in the population. ex. CDC used samples of women's and men's weights to estimate the weight variables - correct answers any observation of a physical, attitudinal or behavioral characteristic. ex. Behavioral scientists study variables like motivation and self-esteem which begin the research process by transforming observations into numbers Discrete Observations - correct answers Can take on only specific values (ex. whole numbers) no other values can exist between these numbers ex. Measuring the number of times participants get up early one week, results would be whole numbers not decimals Continuous Observations - correct answersCan take on a full range of values (ex. numbers with several decimal places) an infinite number of potential values exists ex. measuring in seconds how long it took someone to do something 12.83912 seconds What are 2 types of observations that are always discrete observations? - correct answersNominal variables and Ordinal variables Nominal variables - correct answersAre used for observations that have categories or names as their values ex. Assigning female participants with the number 2 and male participants with the number 1 and the numbers are just strictly used as a name there is no other meaning implied (number one doesn't mean better than number 2 etc...) Ordinal variables - correct answersAre used for observations that have rankings (1st, 2nd 3rd etc...) ex. In talent shows the participant finishes with a ranking which determines if they will go on to get a record deal it doesn't matter if #1 was slightly more talented or much more talented. They are discrete because a singer can be ranked 1st place but not 2.685th What are 2 types of observations that can be continuous observations? - correct answersInterval variables (some can be discrete) and Ratio variables Interval variables - correct answers(can be discrete or continuous) Are used for observations that have numbers as their values; the distance (or interval) between pairs of consecutive numbers is assumed to be equal ex. temperature is an interval variable because the interval from one degree to the next is always the same ex. the discrete variable of how many times someone wakes up in a week early is also an interval variable because the difference between 1 and 2 times is the same as the difference between 5 and 6 times Ratio variables - correct answers(almost always continuous) variables that meet the criteria for interval variables but also have meaningful zero points ex. If someone never has to get up early in the morning this 0 could mean a number of things such as the person is unemployed, retired, ill or on vacation ex. number of times a rat pushes lever for food is a discrete ratio variable because the rat might never push the bar ex. ratio observation that are not discrete happen when crossing the finish line in a race Time always implies a meaningful 0 Scale variable - correct answersA variable that meets the criteria for an interval variable or a ratio variable. (Ratio variables and interval variables are called scale variables) Levels - correct answersAre the discrete values or conditions that variables can take on ex. Male is a level of the variable gender, female is also a level in both cases gender is the variable Independent variable - correct answersHas at least two levels that we either manipulate or observe to determine its effects on the dependent variable ex. studying if gender predicts one's attitude about politics then the independent variable is gender Dependent variable - correct answersIs the outcome variable that we hypothesize to be related to or caused by changes in the independent variable Confounding variable - correct answers(the enemy of good research) Any variable that systematically varies with the independent variable so that we can't logically determine which variable is at work ex. Trying to hypothesize that a diet drug will lead to weight loss but at the same time the person is also exercising then whether the person uses the drug is the independent variable, exercising becomes the potentially confounding variable that we would try to control (can be the other way around too) Reliability - correct answersRefers to the consistency of a measure ex. You get the same answer each time you take a Facebook quiz or you keep getting the same number on the scale when you weigh yourself twice an hour apart Validity - correct answersRefers to the extent to which a test actually measures what is intended to measure ex. Something can be reliable but not valid if it keeps giving the same response each time but the response might not be correct *A measure with poor reliability can't have high validity ex. Rorschach inkblot test: 2 clinicians might analyze the identical set of responses and develop quite different interpretations of those responses = lack of reliability Hypothesis Testing - correct answersThe process of drawing conclusions about whether a particular relation between variables is supported by the evidence ex. examining data from a sample to draw conclusions about the entire population Operational Definition - correct answersSpecifies the operations or procedures used to measure or manipulate a variable. Reporting how you collected the results, in what way did you obtain the information so others can replicate this experiment in the future. Ex. Reporting that you measured people's personality by giving them a survey. ex. operationalizing a good outcome of adopting a dog by asking if they kept it for more than a year, asking them to rate their satisfaction or if the vet gave a high rating of health Correlation - correct answersAn association between 2 or more variables . This is one way to test a hypothesis but it's easier to interpret results in an experimental study rather than in a correlational study Random Assignment - correct answersEvery participant in a study has an equal chance of being assigned to any of the groups or experimental conditions in the study Experiment - correct answersA study in which participants are randomly assigned to a condition or level of one or more independent variables, neither the participant nor the experimenter get to assign these conditions *Experiments are great for hypothesis testing because they are the best way to control confounding variables and is easier to infer a cause-effect relation between variables Between groups research design - correct answersAn experiment in which participants experience one and only one level of the independent variable ex. An experiment that compares a control group (people randomly assigned not to play video games) with an experimental group (people randomly assigned to play video games) Within-groups research design - correct answersAn experiment in which all participants in the study experience the different levels of the independent variable ex. An experiment that compared the same group of people before and after they experience a level of an independent variable such as video gaming "If you experience one condition of a study, then you remain *within* the study until you experience all conditions of a study" This is good with longitudinal studies which observe how organizations or people change over time before and after affects of a hurricane. Outlier - correct answersIs an extreme score that is either very high or very low in comparison with the rest of the scores in the sample Outlier analysis - correct answersStudies examine observations that don't fit the overall pattern of the data in an effort to understand factors that influence the dependent variable Frequency Distributions - correct answersOrganizing raw scores into histograms or frequency polygons or frequency tables (or grouped frequency tables). The way in which raw scores are organized in statistics; this describes the pattern of a set of numbers by displaying a count or proportion for each possible value of a variable. Raw Scores - correct answersBasic ingredients of a data set; data that have not yet been transformed or analyzed Frequency Tables - correct answersA visual depiction of data that shows how often each value occurred meaning how many scores were at each value. Values are listed in one column, and the numbers of individuals with scores at the value are listed in the 2nd column. Once data organized into a frequency table, the data can be displayed as a grouped frequency table, a histogram or a frequency polygon. Frequency Table Procedure - correct answers1) Determine the highest score and the lowest score 2) Create 2 columns, label the first with the variable and name and label the second "frequency" 3) List the full range of values that encompasses all the scores in the data set from highest to lowest, include all values in the range, even those for which frequency is 0. 4) Count the number of scores at each value, and write those numbers in the frequency column. Grouped Frequency Table - correct answersA visual depiction of data that reports frequencies within a given interval rather than the frequencies for a specific value. This is a technique best used to deal with data that goes to too many decimal places (ex. reaction times) Grouped Frequency Table Procedure - correct answers1) Find the highest and lowest scores in the frequency distribution 2) Get the full range of data: If there are decimal places round both the highest and the lowest scores down to whole numbers and add 1 to get the full range of data 3) Determine the number of intervals and the best interval size recommended interval size is 5-10 intervals (To find the best interval size divide the range by the number of intervals we want and then round to the nearest whole number) Normal Distribution - correct answersA specific frequency distribution that is bell-shaped, symmetric and a unimodal curve ex. IQ scores Skewed Distribution - correct answersDistributions in which one of the tails of the distribution is pulled away from the center Positively Skewed Distribution - correct answersThe tail of the distribution extends to the right in a positive direction. There can be a floor effect. The Floor Effect - correct answersA situation in which a constraint prevents a variable from taking values below a certain point ex. World cup success how many times a country got first or second place, few countries get second or first place so data is mostly on the left side and is constrained because the value cannot go below zero Negatively Skewed Distribution - correct answersData, which have a distribution with a tail that extends to the left, in a negative direction. Can have ceiling effect. The Ceiling Effect - correct answersA situation in which a constraint prevents a variable from taking on values above a given number. Ex. If a professor gives a really easy quiz most will get a high score with few getting a bad score, nobody can get more than 100 Stem-and-Leaf plot - correct answersA graph that displays all the data points in a variable (or of 2 levels of a variable) both numerically and visually Biased Scale - correct answerslie where information is slanted in a particular way; scale has 4 positive categories and 1 negative category -- scale is pulling for certain response information is slanted (ex, very good, good, fair, poor. 3 of 5 are positive) Ex. New York Magazine's restaurant rating Sneaky Sample Lie - correct answersnot fully representing the population, only using the people that would create a certain outcome Ex. "Rate my professor" website, students most likely give rating are those who strongly like or dislike a professor = self selected sample=the info might not apply to you Extrapolation Lie - correct answersThis lie assumes that values beyond the data points will continue indefinitely Ex. Students wanted to start teaching students how to use CB radios whose popularity was growing quickly (now mostly used by truckers) but mobile phones were introduced, so it is bad to assume a pattern will continue on indefinitely Interpolation lie - correct answerstendency to assume that some value between data points lies on a straight line between those data points