Design of Experiments - The goal of the project was to constructively design a completely randomized experiment consisting of one independent variable that may affect the performance of a paper helicopter

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Industrial & Systems Engineering

North Carolina A&T State University

INEN 675

Design of Experiments

Dr. X. Jiang

Project 1: Paper Helicopter Flight Time

Group Members:

Miracle Jacobs

Charles Jones

Adrain Kendrick

Raquel Teasley

Jessica Terry

Abstract

The sound design of an experiment is essential to the validity of testing of the topic studied.  Principles of experiment design and testing were explored throughout this project, and the results of the carefully designed experiment, executed with collected and analyzed data, are presented in this report.  The project is two-fold; the execution of a Completely Randomized design in the first experiment, and the Randomized Complete Block design in part two.  The first experiment consisted of a single factor with three levels, where the flight time was the focus of the project.  The team hypothesized that as the levels of the experiment increased, the flight time of the helicopter would decrease.  The second portion of the project investigated how the length of tail of the helicopter influenced the flight time, considering paper stock as a blocking factor.  The team hypothesized that a shorter tail would increase the overall flight time of the helicopter.

Part 1. Completely  Randomized Design

Introduction

        When conducting an experiment, it is critical that the experiment is randomized and that there is replication.  Randomization is one of the most important basic principles of designing an experiment.  When using the principle of randomization, trials are completed in a random order to balance out the effect of “lurking” variables, and to reduce bias.  Lurking variables consist of items that would cause variance to the outcome of the experiment.  Replication helps to reduce random error by improving precision of effect estimation of error or background noise.  Replication consists of multiple copies of the original test design.  The team understood the principles of randomization and replications were imperative to the validity of the experiment.  The conclusive objective formed was to have at least two samples.  

The goal of the project was to constructively design a completely randomized experiment consisting of one independent variable that may affect the performance of a paper helicopter.  After forming the objective, the team brainstormed to decide what variable to use, what the test objective would be, and the number of levels at which it would be tested.  Initially, other testing parameters were considered.  These parameters were the length of the wings, the width of the wings, the length and width of the tail, and the type of paper to be used. The issue that surfaced that did not permit the testing of the parameters stated was limited resources.  After brainstorming, the decision to use the number of paper clips (1, 2, and 3) as the levels was agreed upon.  The following hypothesis was then designed:  Does the number of paper clips have an effect on the flight time?  The team hypothesized that the flight time would decrease, as the number of paper clips increased.  With a well outlined hypothesis, the beginning of the experiment could ensue.

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Materials and Environment

        The materials used to conduct this experiment include: 1 pair of scissors, three paper clips, and 15 sheets of 8.5x11’’ .01lb printable paper, a ruler, and a stopwatch.

        The experiment was conducted in classroom 123 of the McNair engineering building.

Methods

        The proposed null hypothesis (H0 ) was there would not be a difference between the three means; the proposed alternative hypothesis (Ha ) was that at least one of the means would differ.  The independent variable was the paper clips; the dependent variable was the flight time. The steps for the experiment were as followed:

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