KIN 4310 1nd Edition Lecture 6 Outline of Last Lecture I Misuse of Statistics II Definitions III Misleading Graphs IV Pictographs V Misleading Questions VI Experimental Research VII Independent and Dependent Variables VIII Correlation IX Correlation vs Experiment Research X Definition XI Definition XII Exploring the Data XIII Properties of the Linear Correlation Coefficient r XIV Scatter Plots of Paired Data XV Homoscedasticity Homogeneity of Variance XVI Requirements for r XVII Correlation Coefficient XVIII Coefficient of Determination r squared These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute XIX Common Errors involving Correlation XX Correlation Between Gender and Strength XXI Examples Outline of Current Lecture I Workshop II Excel Functions III Objectives Measurement Theory IV Measurement V Terms Measurement VI Measurement Challenges VII Variables of Interest VIII Classical Test Theory O T E Current Lecture variability will be on Exam 1 but it is in the section 2 power point presentations will be covered next week ometer means measure something I Workshop a There s a correlation between hand span and grip strength II Excel Functions a Linear correlation coefficient i CORREL array1 array2 ii array 1 is the data in the x axis iii array 2 is the data in the y axis III Objectives Measurement Theory a Understand operational definitions and be able to identify variables of interest b Distinguish between scales of measurement i Nominal ordinal interval and ratio scales c Define Reliability d The measurement theory is whatever we measure but what we measure is not the real thing i Ex the present example IV Measurement a You need to know that the data you are collecting represent what it is you want to know about b How do you know that the instrument you are using to collect data works every time c And how do you know that it measures what it is supposed to d A lot of measurement are indirect i For example how do you measure depression Or when you weigh fruit at the grocery store V Terms Measurement a Measurement consists of rules for assigning numbers to objects in such a way as to represent quantities of attributes Nunnally 1967 b Most measurement is indirect 1 E g A breathalyzer test measures BAC by shining infra red light though exhaled breath and examining the absorbed wavelength 2 The breathalyzer is the test standard 3 A blood alcohol test is the golden standard c Any system used to measure something VI Measurement Challenges a Assumption 1 x exists b Assumption 2 x is measureable c Issue What is real what is error d Challenges change with the times i Weight gravity time ii Brain damage genetics iii Intelligence depression e How do you measure brain damage How do you measure time a clock VII Variables of Interest a What do you want to know and how can you know it i Hunger thirst ii Pain symptoms iii Healthy unhealthy eating iv Self esteem self efficacy attachment extraversion b Empirical or Operational Definitions What can be measured that best reflects what we want to measure i Hours of food water deprivation ii Infliction of pain vs experience of pain iii Self report of x but what is it really VIII Classical Test Theory O T E a Observed score i The actual score on a test b True score i Theoretical reflection of the actual amount of a trait or characteristic an individual possesses c Error score i Part of the score that is random ii Can be positive or negative d Reliability True Score True Score Error i Don t have to memorize this or use this ii Just understand what it means