Introduction to Statistics in Psychology PSY 201 Greg Francis PhD Department of Psychological Sciences Psychological Sciences Building Room 3174 765 494 6934 email gfrancis purdue edu http www psych purdue edu gfrancis Classes PSY201 index html Study Guide for Exam 1 Exam Date September 27 2010 during the regular class period The exam will consist of 10 15 short answer questions that will usually be similar to the problems on the homework but usually smaller However some of the questions will be essay questions where you must describe a concept You will be expected to perform some calculations so bring a calculator If any tables will be necessary I will provide them Any equations you might need on the exam will be provided but you need to know how to use the equations Know all of the following information Generally you need to both know how to do various calculations and understand the concepts behind the calculations The former you can verify by doing practice problems The latter you can verify by creating a written description of what the calculations are doing If the written description makes sense then you probably understand the concept In general you need to be able to do the calculations discussed in lecture and on the homework assignments For conceptual issues you need to understand the concepts discussed in lecture and the readings will often provide material that will help you do that The TA will hold an outside of class review session in preparation for the first exam on Sunday 26 September 6 00 9 00 pm in LILY Room G401 1 Lecture 2 1 Know the symbolic description of variables and the notation for addition rules of squaring basic algebra 2 Know the distinctions between populations and samples and between dependent and independent variables 3 Know the properties and limitations of the scales of measurement Know examples of each Be able to identify a variable s scale of measurement when appropriate 2 Lectures 3 4 1 Know how to interpret data from a table describing a frequency distribution 2 Know how to build a frequency table from raw data 1 3 Know how to work with exact limits class intervals and similar concepts 4 Know how to find frequency frequency percentage cumulative frequency cumulative frequency percentage 5 Know the meaning of the terms positive skew negative skew symmetry kurtosis Understand their significance 3 Lectures 5 6 1 Know how to calculate percentile rank and percentiles from a frequency distribution table The equations will be given but you must know how to use them 2 Know how to find calculate the mode median both methods and mean Know how they are generally affected by the shape of distribution Know the differences between these measure of central tendency 3 Understand in what sense the different measures of central tendency are the middle of a distribution of scores 4 Know the properties of the mean Know how to compute the mean from combined groups 5 Know how to calculate variance and standard deviation Understand what is being calculated with these measures 6 Know the influence of outliers extreme scores on measures of central tendency and variability 7 Know how to compute z scores also called standard scores Know the properties of z scores Know why you would want to compute z scores 8 Know how to compute transformed standard scores Understand why you would want to in some cases 4 Lectures 7 9 1 Know the basic properties of the normal distribution e g general shape symmetry parameters that define it 2 Know the properties of the standard normal distribution Be familiar with the shape of the exact standard normal 3 Know how to determine the proportion of scores in a specified range using a normal distribution 4 Know how to determine percentiles in a normal distribution 5 Know how to determine percentile ranks in a normal distribution 2 6 Understand and know how to use the Standard Normal Table to find percentiles percentile ranks and proportions The table will be provided on the exam 5 Lectures 10 12 1 Understand the basic idea of correlation and correlation coefficients 2 Know the relationship between scattergrams and correlation 3 Know how to compute the Pearson r The equations will be given but you must know how to use them 4 Know the factors that might affect the size of r linearity homogeneity group size Understand their significance 5 Understand how to interpret r values rule of thumb proportion of variance 6 Know how to calculate the Spearman The equation will be given but you must know how to use it 7 Understand the relationship between and r 8 Understand the relationship between correlation and causality 3 You may find the following equations useful These equations will be available on the exam np cf w PX ll fi P RX cf fi X ll w 100 n n 0 50 cf Mdn ll fi Pn w Xi i 1 X n i ni X i X P i ni P P 2 s 2 Xi2 i Xi 2 n n 1 P P i s X 2 n 1 i Xi Xi2 i Xi 2 n n X X z s X sz X P zx zy rxy n 1 P xi yi rxy qP P x2i yi2 2 rxy rh P n n P i P i Xi Yi P i Xi2 P i P i P Xi i ih P 2 Xi rxy r2 n sxy sx sy s2A s2Y 6 i d2i 1 n n2 1 P 4 i Yi Yi2 P i Yi 2 i