DOE Hypothesis Testing

INTRODUCTION

My team members:

• Kalyani
• Brayden
• Jolyn
• Gideon

FULL FACTORIAL DESIGN DATA

FRACTIONAL  FACTORIAL DESIGN DATA

• Kalyani will use RUN #4 from FULL and FRACTIONAL design data.
• Brayden will use RUN #4 from FULL and FRACTIONAL design data.
• Gideon will use RUN #4 from FULL and FRACTIONAL design data.

Runs I will be testing will be RUN #3 from FULL & FRACTORIAL design data.

The catapult (the ones that were used in the DOE practical)manufacturer needs to determine the consistency of the products they have manufactured. Therefore they want to determine whether CATAPULT A produces the same flying distance of projectile as that of CATAPULT B.
Scope of the test➤The human factor is assumed to be negligible. Therefore different user will not have any effect on the flying distance of projectile. Flying distance for catapult A and catapult B is collected using the factors below: Arm length =  _24.1___cm Start angle = __20___ degree Stop angle = __60___ degree

STEP 1 

Null Hypothesis (Ho): 

U1 = U2

This means that different user will not have any effect on the flying distance of projectile.

Alternative Hypothesis (H1):

U1 ≠ U2

This means that different user will have an effect on the flying distance of projectile.

STEP 2

Full Factorial:

n = 8

X = 120.5 cm

s = 2.90

Fractional Factorial:

n = 8

X = 186.6 cm

s = 3.85

Sample size is 8. Therefore, t-test will be used.

Since the sign of H1 is ≠, a two-tailed test is used.

Significance level used in this test is 0.05.

STEP 3

Standard deviation and mean of Catapult A is 120.5 cm and 2.90.

Standard deviation and mean of Catapult B is 186.6 cm and 3.85.

U1 = Catapult A

U2 = Catapult B

V = 8 + 8 - 2 = 14

A = 0.05/2 = 0.025

At V = 14, t0.975 = 2.145 and -2.145

STEP 4

Hence, at t = -36.28, Ho is REJECTED.

CONCLUSION

According to the above results, it can be concluded that different users has an effect on the flying distance of the projectile.

In Kalyani case, she too has her Ho rejected which also means that different users has an effect on the flying distance of the projectile.

Some inferences I can make is the for both catapult, the tension of each rubber band is different which then results in affecting the flying distance of the projectile. Some rubber bands are tighter or looser which affects the tension at the joint of the arm and the pivot. Another inference is the start angle of the catapult arm, one of our catapult arm goes further than 0 degrees while one is exactly is at 0 degrees. Hence, it could be one of the factor that affected the flying distance of the projectile.

REFLECTION

After completing the hypothetical testing activities, all the exercises, practical questions and this blog. I have a more clear understanding on how hypothesis are tested and the different information required. I still have some trouble remembering the different symbols and what they represent, but with more practice I will be able to get more used to it. In the beginning, I kept on forgetting on making the null and alternative hypothesis. However, after many practices, it became the habit to hypothesise first for every problem. Overall, I enjoyed learning about hypothesis testing and hope to further apply this in my project’s DOE and future design products.