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# PSYC 210 Exam 1 Study Guide 210

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This 22 page Study Guide was uploaded by Victoria Snow on Sunday September 18, 2016. The Study Guide belongs to 210 at University of North Carolina at Chapel Hill taught by Dr. Harrison in Fall 2016. Since its upload, it has received 144 views. For similar materials see Statistical Principles of Psychology in PSYC at University of North Carolina at Chapel Hill.

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Date Created: 09/18/16

PSYC 210 EXAM 1 STUDYGUIDE 9/18/2016 About the exam: - All multiple choice - Bring a scantron - Do NOT have to memorize formulas - Know the CONECEPTS - Not math/calculation based NOTES: Week 1: . Variable- thing that is studied, can have different values
. Measurement- orderly assignment of numbers to characteristic
. Data- observation (behavior/characterstic in psych) coded into categories. Usuall
numeric. 1. Nominal- naming scales (Ex: Genderm=1 f=2)
2. Ordinal - order, numbers don’t imply equal spaces between each value. (Ex: class rank,
1>2>3, but 1 could be a lot higher than 2 and 2 and 3 could be very close to each other)
3. Interval - interval scaleequal spaces between each.
4. Ratio - has 0 as a value and with equal intervals
Rounding- For continuous variables, need to define the # of acceptable digits and decimals. *Normally on APA, 2 decimal points is the rule3.96.
Week 2: Variablitity- how much do peoplediffer from the average Wider=more variability. N=8, less variablity N=2, greater variability Skewness: Where mostof the casesfall -4 -2 0 2 4 Positive skew-
(if rotate 90 degrees clockwise, looks like a “P”) Negative skew- Kurtosis - shape and layout of distribution Basic Definitions: . - Frequency: number of responses that fit a particular category of level of a variable
. - Cumulative frequency: number of responses at or previous to that response. Adding
as you go. The last category is always the entire sample
. - Relative frequency: proportion/percent. The frequency relative to total number of
responses. Always between 0 and 1.
. - Cumulative Relative Frequency: the proportion of case/responses at or below the
current level of variable. Less likely to be used.
Week 3: CentralTendency-singlenumber descriptors, most common way of describing sampledata -describe by its most common/central/typical response -most common=mean -mean=x̄=x bar Mean=average - Mean means: - Kinda likethe midpoint in a seesawthat balances the distribution - Good singledescriptor - Even better when comparing groups - “unbiased” estimator of the population: μ (“mew”) - Very useful - Is most affected by outliers -The sum of the deviations from the mean will always equal 0. Meanminimizesdeviations Median-point that splitsthemedian in half - Good to use when you have extreme outliers - With odd numbers, middle data point - With even numbers, averageof 2 middle points - Good when you haveskewed data Problem- interval data - Means and medians reallyonly make sensewith interval data The mode isthe best/only thing to use with nominal/ordinal data - Most frequent response - Works for all measurement data Variability-difference from central tendency Range=max-min Variance=avg.standard deviation from the mean Standard deviation=square-rootof the averagesquared deviation from the mean 2 s =variance; sum of the squared deviations from the mean divided by n-1 (samplesize-1) s =standard deviation; the square root of the variance. Puts scores backinto normal scale units. -mean (centraltendency)~ bestguess -variance/variability~how goodof a guessthebestguessis.(if std deviation is 0, then that is BESTguess…thehigher thevariance,the more“off”themean is) Week 4: Relativestanding-whereyou fall incomparison to other things Ex: Statue height. Lady Liberty compared to other statues. Percentilesand percentilemarks-relativestanding ofscores insample. Ex: Ifyou’re in the 80 percentile, you arehigher than 80% of people in that value/category. -Percentile Ranks describe what a particular data point means relative to other data points. -The Pth percentile point is the valuebelow which the proportion of the cases fall -P.75 point below which 75% of the scores fall P( N ) n X = L+ [ b i ] n w X= Percentile point L=lower real limit P= percentile rank of required point N= total samplesize n(w)= number of cases withinreal limits n(b)= number of cases falling belowL i=sizeof score measurement unit To usethis formula: Order (ascending)cases byscorevalue Determine N Determine location of desired point o CalculateP(N)-round to desired precision o Locate P(N)th caseindistribution Determine other required values o N(w)= number of cases atdesiredpoint o N(b)= number of cases belowpoint o L=lower real limitof point o i =level of precision of measurement (1for whole numbers, .01 for two decimal places,etc.) What percentileisagiven score? n w X L + (i)()n ) b P = (N ( ))i All same variable X= your score P= percentile you are in -Transforming things to Z scores allows us to compare across different samples with different characteristics-itequates the two distributions -Equates the means by making them 0 and equates std dev. by making them 1 X i X Z for sample Z = s x X Z = i X Z for population X Making theZ score: -First, the numerator of the Z transformation equation creates new distribution with mean of 0. - Referred to as “centering” a variable. - Makes the mean equal to 0 -Second, dividing by standard deviation creates a new distribution with a stddev of 1.0 In a normal distribution: Mean=0 S=1 Total area under curve=1.0 Curve is symmetrical Usecurve to estimate the proportion ofscores that should fall at/below any given z score TableA (p. 470) provides proportions for Z scores Example 1: 1) Calculate13hours z score: a. Z=(13-9.06)/6.32= 0.623 2) Look up 0.623 in Z table 0.2324= 23.2% above mean 3) Add 0.5 (to account for those below the mean) + 0.2324 0.7324 = 73.2% or the 73 percentile Exam 1 Review 9/16/2016 CentralTendency Mean- average Median- the middle number. 50 percentile. Mode- the most frequent Usemedian as central tendency when there are outliers becausemean is affected by the outlier Mode is good to usewhen the data is nominal Mean and median only work for interval data and ratio data Negativeskewed- mean, median, mode Positiveskewed- mode, median, mean Groups: graphing, central tendency, variability, relativestanding (percentile), Z score Graphing: - Which scales arethe most appropriate to use - Skew- positive/negative - Difference between a bar graph and a histogram - Kurtosis- leptojurtic (tall and skinny) mesokurtic (normal) platokurtic (flat) Central Tendency: - If mean, median, and mode are all equal,what canyou expect from distribution? Normal distribution Variability: - What is the standard measure of variability? Range,variance,standard deviation - When is the mean most useful? When there is less variability - Standard deviation is the square root of the variance(but exam will not even be that “mathy”) RelativeStanding (percentiles): - What it means ifsomeone is atthe 75 percentile? 75% of people are below that person inthat category th - 50 percentile is the median - What is the lower real limit? Thelowest number that could possiblybe considered in that interval or number. Relativestanding (Z scores): - Z scores-why arethey useful? You cancompare different groups that may have different distributions - It standardizes scores - In a normal curve, mean=0, stddev=1, and everything under the curve=1.0. Kahoot Review Game: Questions and Answers 1. Mode is a measure of ___________. Hide answers Kurtosis Variability Skewness Central Tendency 2. What is the primary purpose of graphing data? Hide answers To confuse consumers who may be interested in your data To get a "lay ofthe land" and see what the data look likeTo perform complex statistical tests Tomakesure you havea normal distribution 3. Relativefrequency could be better conceptualized as __________. Hide answers Total Missing data Percent Sum of all points before a certain number 4. What is the exactmiddle point ina distribution? Hide answers Mean Mode Standard Deviation Median 5. Histograms are useful when... Hideanswers you have nominal data you have ordinal data you have interval data when you have disordinal data 6. What type of scalehas EQUAL intervals between responseoptions? Hide answers Nominal Ordinal Interval None of the above 7. Kurtosis broadly refers to ___________. Hide answers the sizeof a distribution the frequency of a particular response the shape of a distribution the measures ofcentral tendency 8. A positivelyskewed distribution has more cases onwhat sideof the graph? Hideanswers The right Theleft 9. What can you do to make a distribution with a lot of different numbers make sense?Hide answers Useclass intervals Omitneedless data Useconfidence intervals Describeit inwords 10. How do you determine the sizeofa class interval? Hideanswers Stats books have different recommendations Theoretical reasons Simple groupings of numbers (i.e., by fives) Divideby 11 11. How would you describe cumulative frequency inone word? Hide answers Adding Dividing Subtracting Listing 12. What piece of output ina frequency tableis probably leasthelpful? Hide answers Relativecumulative frequency Relativefrequency Cumulative frequency Frequency 13. IfI was interested inmeasuring your political party affiliation,what scalewouldbe best? Hide answers Nomial Ordinal Interval Ratio 14. IfI askedyou "How liberal are you on a scalefrom 1to 7?" what scaleshouldI use? Hide answers Nomial Ordinal Interval Ratio 15. Amount of money donated to charity would be bestmeasured using a _________scale. Hide answers Nominal Ordinal Interval Ratio 16. IfI askedyou to rank your top ten favorite movies, I'duse a ______scale. Hideanswers Nominal Ordinal Interval Ratio 17. A frequency histogram is made up of ________. Hideanswers Lines Dots Bars Numbers 18. A frequency polygon is made up of ________. Hide answers Dots Lines Bars Numbers 19. Real limits are_______________. Hide answers upper and lower boundaries for class intervals upperand lower boundaries for central tendency upper and lower boundaries for data upper and lower boundaries for polygons 20. What is one reason we might careabout cumulative frequency? Hide answers To seewhat percent fall atthat interval To seeifwe havemissing data To determine what type of analysis wewill useTodecide what type of scalewewould use 21. What type of distribution is long and flat? Hideanswers Leptokurtic Mesokurtic Platykurtic Something else-kurtic 22. What type of distribution is tall and narrow? Hide answers Mesokurtic Leptokurtic Platykurtic Kurtosis is stupid 23. The purpose of statistics (inour case)is to__________. Hideanswers confound our enemies with numbers simplifyotherwise complex numbers impress our friends and enemies with numbers turn concepts into numbers 24. When a distribution is NEGATIVELYskewed, what order (leftto right) are mean, median, and mode Hide answers median, mode, mean mode, mean, median mean, median, mode mode, median, mean 25. What is your favorite class sofarthis semester? Hide answers STATISTICS! ohhh YEAH! STATISTICS (but I'mreally lying) anything but STATISTICS Other ReviewinClass:QuestionsandAnswers REVIEW QUESTIONS (SHORTANSWER) 1. Ifyou conductedastudywherethenumber1representedmaleandthenumber2represented female,whattypeofgraphwouldyouuse? Bargraph 2. Thestatedlimitsare0-5, 6-10, 10-15. What are thereal limits? 0-5.499, 5.5-10.499, 10.5-15.499 3. What’sthe differencebetweenafrequencygraphandacumulativefrequencygraph? Frequencygraphshowshowfrequenteachvalueisinthegivendataset.Acumulativefrequency graph showsthefrequencyofeachvalueastheyareaddingtogether,soto thelastwillbeequalto thetotal valuesinthegivenset. 4. What isuniqueaboutahistogram’sdesignincomparisontoabargraph? A histogramasno space betweentheintervalsandabar graphis nottypicallyusedforintervals,and has spacesbetweeneachbar. 5. Ifthe graph ispositivelyskewed-whereisthebulkofthedata?Leftorright? Left 6. What type of graph would best represent a setof data with discrete variables? Bar graph 7. Which type of kurtosis indicates the greatestamount of variability? Platykurtic 8. What does the highest point on a histogram represent? The most frequent response/data value mode 9. How are the measures of central tendency ordered in a graph that is positivelyskewed? Median, Mode, Mean Mode, median, mean REVIEW QUESTIONS (MULTIPLECHOICE) 1. You have a data setin which most of your values are between four and 10 but the maximum is 30.What is the skew? a)Negative b) Positive c)Neither 2. What is the kurtosis of the graph? a)Mesokurtic b) Platykurtic c)Leptokurtic d) Neither 3. If you had a data set of people’s favorite subjectin school, how would you graph it? a)On a bar graph b) On a piechart c)On a polygon d) On a histogram e)More than one answer 4. If you had a data set of how many drinks per week people inyour class drank,how would you graph it? a)On a bar graph b) On a piechart c)On a polygon d) On a histogram e)More than one answer 5. If you had a positivelyskewed graph, from leftto right, where would your central tendencies be? a)Median, mean, mode b) Median, mode, mean c)Mode, median, mean d) Mean, median, mode 6. What measurement of central tendency would you usefor nominal data? a. Mean b. Median c.Mode D. Sum 7. What does central tendency represent in a sample? a. Typical response b. best answer c.sum d. explanation 8. Which measure of central tendency works with ALL measurement scales. a. Mode b. median c.sum d. mean 9. What measure of central tendency is most affectedby skewness? a.Mean b. median c.sum d. mode 10. When the graph is skewed negativewhere is the mean in relation to the mode? a. < b. > c.= 11. What other name do Central Tendency go by? a.Single number descriptors b. CT c.Variance d. parameter (answerSingle Number Descriptors) 12. What does the mode tell us? a. A) What the average of the data is. b. B)The data valueappears the most. c. C)I don’t know. Ididn’t pay attention to class. 13. If you have a nominal data setwhich measure of central tendency is bestto use? a. A) The mean b. B)The mode c. C)Whatever Patrick tells us d. D)The median Usethe following graph to answer the following 2 questions. 14. What type of graph is this? a. Normal Distribution b. Negativelyskewed distribution c. Positivelyskewed distribution d. I don’t know. Patrick confused us. e. Bimodal graph 15. Order the following measures of central tendency inorder from most valuableto least valuablefor this type of graph: mean, median, mode. a. Mode, median, mean b. Median, mode, mean c. Mean, median, mode d. Median then mode. Don’t use mean Usethe following graph to answer the following 2 questions. 16. What type of graph is this? a. Kurtosis b. Positivelyskewed graph c. Negativelyskewed graph d. A graph that shows only the mode values. 17. Order the following measures of central tendency inorder from most valuableto least valuablefor this type of graph: mean, median, mode. a. Mode, median, mean b. Median, mode, mean c. Mean, median, mode d. Median then mode. Don’t usemean 18. If you have skewed data, which measure of central data is the most impacted? a. Median b. Mean c. Mode d. You can’t usea measure of central tendency for skewed data 19. If you have skewed data, which measure of central tendency is leastimpacted? a. Mean b. Mode c. Median d. All of the above 20. What measure of central tendency is bestfor comparing data sets. a. Median b. Mean c. Mode d. None of the above 21. Which measure of central tendency minimizes deviations? a. Mode b. Mean c. Median d. Kurtosis 22. In a normal distribution, how percent of data falls under the curve and behind the mode? a)100% b) 75% c)50% d) Not enough information 23. What is the name of the balancepoint and center point of a graph of a distribution? a. median, range b. mean, median c. standard distribution, mean d. median, mean 24. What type of data is itbestto usemode for? a. interval b. nominal c. ordinal d. all data 25. When data has an outlier present, what type of central tendency measure is bestto use? a. mean b. median c. mode 26. What is the order of mean, median, mode in a negativelyskewed distribution? a. mode, median, mean b. mean, median, mode c. mode, mean, median d. d) median, mode, mean 27. Which measure of central tendency is bestusedfor nominal data? a. mean b. median c. mode 28. True/False: Measures of central tendency are singlenumbers that describea distribution 29. What does nbrepresent? a. Number within real limit point b. Number of cases falling belowL c. Size of score valuemeasurement unit d. Total samplesize 30. What is a lower real limit? a. The lowest scorein the data set b. The maximum score minus the minimum score c. The lowest scorethat could be rounded up to the desired percentile point d. None of the above 31. Why is using thelower real limitin calculating percentiles necessary? a. You need to choose the same limits sothe equation solution canbe solved consistentlyby different people b. You need to define the boundaries of your category c. Both Aand B d. None of the above 32. How does data transformation relate to the mean and variance? a. Changes them by multiplying and adding a constant b. Increases mean while decreasing variance c. Changes them by subtracting and dividing a constant d. Decreases both the mean and therefore the variance 33. What is the first stepin calculating percentile rank? a. Determine N b. Order cases bydescending value c. Determine Nw and Nb d. Order cases byascending value 34. What values do you need to determine in order to calculatepercentile? a. Nw, nb, X, L,P, E b. Nd, X, L, nb, P, i c. Nb, P, X, E, I,Nw d. None of the above 35. If you want to determine the percentile rank of a your own score,what valuedo you need to solvefor? a. P b. X c. N d. E 36. Whichof theseisnota measureofvariability? a. Mean b. Range c. Variance d. StandardDeviation 37. Whichof theseistrueaboutvariability? a. Sampleswithlotsofvariabilitywillmeanthatourmeancan be prettyfarawayfromsomeof ouractualscores. b. Sampleswithalittlebitofvariabilitywillmeanthatourmeancan beprettyfaraway from someofour actual scores. c. Sampleswithlotsofvariabilitywillmeanthatourmeancan beclose fromsomeofouractual scores. 38. What can be describedasanestimatorforpopulation? a. Statistics b. Samplesize c. Median d. Sigma 39. How doyou findthestandarddeviation? a. The squarerootof thevariance b. Themaximumminustheminimum c. Addingalldatapointsanddividingbythesample d. Themost commonanswer 40. What is variability? a. It describes the shape of the distribution b. The degree to which scores differfrom eachother and from central tendency c. the average of data in a set d. the chance that Patrick numbers 1-6 incorrectly 41. What are the 3 standard measures of variability? a. Range,variance,standard deviance b. Mean, median, mode c. Standard deviation, central tendency, all data d. Z-score,sigma,mu 42. The ________of variance is the _________. a. Standard deviation; square root b. Square root; standard deviation c. Average; percentile d. Distribution; percentile 43. What is the difference between central tendency and variability? a. A b. B c. C d. Central tendency is the bestguess for the data; variance tells how good that guess is 44. Varianceis limited by the range a. False b. True 45. What does the term “variability” mean? A. the degree to which the scores in a sample differ from one another B. the average deviation from the mean in a sample C. the central tendency of a sample 46. Which of the following are statistical measures ofvariability? A. Range B. Standard Deviation C. Variance D. All of the above 47. How does standard deviation differ from variance? A. Standard deviation is the square root of the variance B. Standard deviation is the variancesquared 48. What does the standard deviation tell us? A. The averageamount by which individuals in the sample vary from the mean B. The averagesquared deviation from the average C. how “good of a guess” themean is (how well the mean represents the sample) D. Both Aand C 49. What is the range? A. a measure ofvariability B. the difference between the highestscore and the lowest score C. Both Aand B D. the mean 50. What puts things into perspective (in relation to other things)? a. Relational standing b. Relativestanding c. Percentile d. Indicator 51. Relativestanding of scores in samples are a. Z scores b. Intervals c. Percentiles and Percentile Ranks d. Population Parameters 52. Which of the following does RelativeStanding not use a. Standard Normal Distribution b. Z scores c. Statistics d. Percentile 53. If you are in the 80 percentile what does that mean? a) You are below 80% of the rest of the students b) You are above 80% of the rest of the students c) You scored an 80% on the test d) You are 80 years old 54. Which of the following is correct when talking about “L” inthe percentile formula? a) It is standing for “love” to represent our communal love for statistics b) It is a setvalue for any equation c) It is created by establishing what the highestpoint an answer could be correct d) It is created by establishing what the lowest point ananswer could be correct 55. True or False:Relativestanding puts things in perspective. a) True b) False 56. What does P35ean? a. 35% of the samplefalls ator below that point b. 35% of the samplefalls abovethat point c. 35% is cool 57. What is the percentile of the median? a. 7654 b. 50 c. 3 58. What does the Pth percentile point describe? a. The valuebelow which the proportion P of the cases fall b. The valueof the proportion P c. The total samplesize d. The number of cases falling withinthe real limits of the score value containing the percentile point Answers: (note:thesearewhatIthink arecorrect withtheinformationgivenfromnotes andlecture. Notconfirmedto becorrect fromprofessor) 1-b 2-a 3-e 4-d 5-c 6-c 7-a 8-a 9-a 10-a 11-a 12-b 13-b 14-c 15-b 16-c 17-b 18-b 19-b 20-b 21-b 22-c 23-b 24-b 25-b 26-b 27-c 28-True 29-b 30-c 31-c 32-a 33-d 34-d 35-a 36-a 37-a 38-a 39-a 40-b 41-a 42-b 43-d 44-true 45-b 46-d 47-a 48-a 49-c 50-b 51-c 52-c 53-b 54-d 55-a 56-a 57-b 58-a

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