Experiment 1 - Application of Statistical Concepts in the Determination of Weight Variation in Samples

APPLICATION OF STATISTICAL CONCEPTS IN THE DETERMINATION OF WEIGHT VARIATION IN SAMPLES

A. J. CAPUNO1

1INSTITUTE OF BIOLOGY, COLLEGE OF SCIENCE

UNIVERSITY OF THE PHILIPPINES DILIMAN, QUEZON CITY 1101, PHILIPPINES

DATE SUBMITTED: 3 FEBRUARY 2016

DATE PERFORMED: 29 JANUARY 2016

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1. What is the significance of Grubb’s Test?

The Grubb’s Test (1) is a statistical test that is used to test out normally distributed records for outliers. Grubb’s test can be used to verify whether or not a single outlying value within a set of data has the largest absolute deviation from the mean. As such, it is applied to either the lowest or highest value in the set (suspected outliers); only one value may be removed from the set on the basis of Grubb’s test. [1] Grubb’s statistic G is then calculated as:

(1)

G= maxi=1, n| Xi- X |s

Xi = suspected measurement

X = arithmetic mean

s = standard deviation

The use of the test is quite simple and straightforward: one solves for the absolute value of the difference of the minimum/maximum value of the set and the computed arithmetic mean. The result is divided by the standard deviation of the sample. If the resulting test statistic G is greater than the critical value, the corresponding value can be regarded to be an outlier and therefore omitted from the sample. Otherwise, suspected value will still be included in the set of data. [2]

2. What is the significance of the mean and standard deviation?

The mean, or simply average (2), is the summation of all raw data of the sample divided by the number of sample. Together with median and mode, these three are the common measures of central tendency. Central tendency is defined as “the statistical measure that identifies a single value as representative of an entire distribution.”[3] It seeks to provide a single representative value of the entire collected data. The mean utilizes...