introduction

Welcome to OT1102 subgroup 4's Statistics data blog. Team members: Vivien Kwa, Shermaine Lau, Feng Rui, Brenda Yap & Alicia Lim. Credits for layout: doughnutcrazy Rationale of study: to determine if an individual's BMI correlates to his/her height.

research hypothesis (H1): There is a positive relationship between an individual’s height and Body Mass Index (BMI).

null hypothesis (H0): There is no relationship between an individual’s height and BMI.

Dependent: Body Mass Index (BMI).

Independent: Height.

Extraneous: Age(Nominal), Gender(Nominal) & Timing of measurement(We measured all our subjects before lunch).

In our research, height means how tall a person is. Height is defined as the measurement of a person standing upright against a flat wall from the base of his heel to the tip of his head in centimeters (cm). Weight is taken by using a weighing scale placed on a floor in kilometers (kg). BMI is is a measure of a person's weight in relation to height.

Height is taken twice both using a vinyl measuring tape, to the nearest 0.1cm. Weight is taken twice using both a electronic weighing scale and an analogue weighing scale, to the nearest 0.1kg. BMI is calculated by taking weight in kilograms divided by height in centimeters squared times 10,000

On 1st June 2012, we gathered at Nanyang Polytechnic, School of Health Sciences, Block H, Level 5, Room 04 for our data collection. We planned to collect a sample of 30 participants with no gender preference. Participants were picked at random in a population of 55 Occupational Therapy Year 2 students. No person rejected when approached to be a subject for the data collection. Before the experiment,all 30 participants gave verbal consent to have their height and weight taken. All measurements were taken at one go, and the timing was before lunch (as food will affect the weight measurement). We used 2 vinyl measuring tape and 2 weighing scale, both analogue and digital weighing scales. Inter-rater reliability is ensured by having the measurements taken by two different group members. The measurements taken were written down on a table below.

the measuring tape was set up against the wall and made to be as perpendicular to the floor as possible. We measured 100.0cm from the ground using the measuring tape before making a mark on the wall. The 0.0cm on the measuring tape was then moved up to the mark on the wall. We did this as one measuring tape itself was not long enough to measure a person’s height. Standardization was achieved as the same one person did the setting up for both height measurement stations. During height measurement, we had the same two persons to take the measurement so as to eliminate discrepancies as much as possible. Each subject was instructed to stand with his/her back straight against the tape measure that was set up, and an appointed group member measured the height from base of feet to top of head. In order to take accurate height measurement, we used a metal ruler to mark out the height. Measurements were written down on a piece of paper and the average was calculated.

we ensured the consistency in the persons taking the measurements. The weighing stations were set up by placing both weighing scales next to each other on the ground of the room. Each subject had to step onto the electronic weighing machine first and the appointed group member had to jot down the measurement on a piece of paper. After that, the subject proceeds to step on the analogue weighing scale. The group member that was in-charge of jotting down the weight using the analogue weighing machine had to look at the scale from top down in order to reduce parallax error. Measurements were written down on a piece of paper and the average was calculated.

According to the scatter plot drawn below, there is a linear relationship between the height and the BMI variables which are both scale measurement, thus we’ve decided to use the Pearson’s r statistical test to look at the linear relationship.



Not assuming the null hypothesis, Using the asymptotic standard error assuming the null hypothesis & Based on normal approximation.

Pearson's R is 0.168, P is 0.379. Pearson's R value (<0.2) indicates a very weak relationship. Since P>0.05, we accept the null hypothesis (Ho).

We surveyed 30 subjects(n=30). After analyzing our data, we deduce that in total, Pearson's R = 0.168, p= 0.379 (>0.05). Therefore we accept the null hypothesis & conclude that there is no positive relationship between an individual's BMI and his/her height.