Anthropometry Practical

Write Up You are provided with all the data from this year and previous years You should use the data to produce a short research paper for the fictitious journal: Journal of Nutrition, Metabolism & Disease In your paper you should explore – Compared to the Bodpod how do the other methods perform? – Does this differ between males and females?

Analysis of Data Assume BodPod is the reference method Perform Statistical analysis using ANOVA in SPSS (see next slide) Perform a correlation between BodPod and each of the other methods using EXCEL

Correlations in Excel Select columns to compare (e.g. Bod Pod vs Omron) Highlight the 2 columns Select Insert – Scatter Scatter with only markers Click on a data point and then select add trendline Select linear, display R 2 and display equation

Statistical Analysis in SPSS U of N Software Statistical and Mathematical SPSS (PASW) IBM SPSS Statistics 22 Type in Data then OK Switch to Variable View Name – Row 1- Subject Row 2- Method Row 3- BodyFat Switch to Data View Copy and paste Data into appropriate columns from Excel Speadsheet- Data for Stats Select Analyze Compare means One-way ANOVA Select BodyFat as Dependent List Select Method as Factor Continued

Options Tick Descriptive Select Continue Post Hoc Tick Dunnett Control Category –select Last Select Continue Select OK Output First table is descriptive stats and will tell you the mean for each method and other variables such as standard deviation Second Table is overall outcome of ANOVA – a significance (sig) value less than 0.05 means there are differences between the groups Third Table is result of ‘Post Hoc Tests’ and compare each of the other methods with Method 5 (BodPod). A significance (sig) value of less 0.05 means that method is giving significantly different values to the BodPod

Average value for each of the methods Standard deviation Often used to show the variability of the data in tables and graphs Number of subjects

Standard Deviation

If value is less than 0.05 then statistically different. The lower the value the more significant This tests to see if there are any differences between the methods. It does not tell us which method is different from which Would normally be referred to as p<0.001

If value is less than 0.05 then statistically different. The lower the value the more significant This test is comparing each of the methods with BodPod (method 5)

Correlations in Excel Copy and paste required data (see excel spreadsheet) Highlight the columns Select Insert – Scatter Select Scatter with only markers Click on a red data point and then select add trendline Select linear, display R 2 and display equation Repeat with a blue marker

Accuracy & Precision Accuracy – How close is are the values to the actual value – In our case how close is the value to that given by the BodPod (measured in ANOVA & equation for the line) Precise – How reproducible is a measurement – In our case this is reflected in the r 2 value for the line – The close to 1 the value the more precise the data – Significance depends on number of data points Males (n=30) anything over 0.14 is significant Females (n=129) anything over 0.03 is significant

Precise Perfect Data Data goes through origin

Precise Data Data not going through origin

Accurate Data Accurate less precise

Horrible Data Not Accurate Not Precise Not going through origin