Statistical Refresher PDF

REFRESHER ATISTICAL ST PSYCHOLOGICAL ASSESSMENT I DIANA VIA PANAL, RPM WHAT IS STATISTICS?  MEASUREMENT an act of assigning numbers/symbols to characteristics of things accor...

REFRESHER ATISTICAL ST PSYCHOLOGICAL ASSESSMENT I DIANA VIA PANAL, RPM WHAT IS STATISTICS?  MEASUREMENT an act of assigning numbers/symbols to characteristics of things according to rules. SCALE a set of numbers/symbols whose properties model empirical properties of the objects to which the numbers are assigned.  TYPES OF SCALES DISCRETE SCALE CONTINUOUS SCALE consists of distinct and separate values values/variables can take any variables/values that are countable number within a given range used to categorize data into groups EXAMPLE: HEIGHT, WEIGHT, TIME EXAMPLE: (GENDER, NUMBER OF CHILDREN IN A FAMILY  ERROR -refers to the collective influence of all the factors on a test score or measurement beyond those specifically measured by the test.  SCALES OF MEASUREMENT 1. NOMINAL SCALES -simplest form -used for classification or catergorization  SCALES OF MEASUREMENT 2. ORDINAL SCALES -rank ordering on some attribute  SCALES OF MEASUREMENT 3. INTERVAL SCALES -equal intervals between numbers but no true zero point.  SCALES OF MEASUREMENT 4. RATIO SCALES -true zero point. -with meaningful mathematical operations. DESCRIBING DATA DISTRIBUTION -set of test scores used for recording or study. RAW SCORE -unmodified accounting of performance (numerical).  FREQUENCY DISTRIBUTION -table/graph that displays how frequently different variables occur in a dataset.  MEASURE OF CENTRAL TENDENCY is a statistic that indicates the average or midmost score between the extreme scores in a distribution.  ARITHMETIC MEAN -sum of observations divided by the number of observations  MEDIAN -middle score in a distribution  MODE -most frequently occuring score ACTIVITY FIND THE MEAN: Height of 10 students: 150 cm, 155 cm, 160 cm, 165 cm, 165 cm, 170 cm, 175 cm, 175 cm, 180 cm ACTIVITY FIND THE MEDIAN: Ordered heights (ascending order): 150, 155, 160, 165, 165, 170, 175, 175, 180 ACTIVITY FIND THE MODE: 150, 155, 160, 165, 165, 170, 175, 175, 175, 180  MEASURES OF VARIABILITY -statistics that describe the amount of variation in a distribution VA RIA NGE ES RA TIL INTERQUARTILE AR NC QU RANGE E  VARIABILITY -an indication of how scores in a distribution are scattered or dispersed.  RANGE --difference between highest and lowest scores --RANGE= HIGHEST VALUE - LOWEST VALUE Imagine, you are planning a vacation to and want to decide what clothes to pack. You check the daily high temperatures for the past week: MON: 70 C TUE: 65 C WED: 75 C THURS: 68 C FRI: 80 C SAT: 72 C CALCULATE THE RANGE. SUN: 78 C  QUARTILES --divide points into four equal parts SALARY DISTRIBUTION IN A COMPANY A company with 100 employees and their annual salaries are collected. The salaries are distributed as follows: Lowest salary: Php 50,000 Median salary: Php 70,000 Highest salary: Php 90,000  INTERQUARTILE RANGE --difference between Q3 and Q1.  VARIANCE --measure of score spread relative to the mean EXAM SCORES VARIANCE A teacher has two classes and she gives both classes the same exam. The scores for each class are as follows: Class A: 60, 62, 64, 66, 68 Class B: 50, 60, 70, 80, 90 STEP-BY-STEP CALCULATION OF VARIANCE: 1. FIND THE MEAN FOR EACH CLASS 2. SUBTRACT THE MEAN FROM EACH SCORE 3. SQUARE THE DIFFERENCES SKEWNESS IN DATA -an indication of how the measurements in a distribution are distributed  POSITIVE SKEW -scores fall at the high end of the distribution  NEGATIVE SKEW -scores fall at the low end of the distribution