### How to analyse data using Stata

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2. drtamil@gmail.com STATA - compute A study to identify factors that can cause small for gestational age (SGA) was conducted. Among the factors studied were the mothers’ body mass index (BMI). It is believed that mothers with lower BMI were of higher risk to get SGA babies. 1. Create a new variable mBMI (Mothers’ Body Mass Index) from the mothers’ HEIGHT (in metre) & WEIGHT (first trimester weight in kg). mBMI = weight in kg/(height in metre)2. Calculate the following for mBMI; – Mean – Standard deviation Copy and paste your answers into your Word file.
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4. drtamil@gmail.com Mean & Standard Deviation
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7. drtamil@gmail.com Stata - Recode 2. Create a new variable OBESCLAS (Classification of Obesity) from mBMI. Use the following cutoff point; – <20 = Underweight – 20 – 24.99 = Normal – 25 or larger = Overweight • Copy and paste these commands into the STATA command window ======================== gen OBESCLAS = 1 if mBMI< 20 replace OBESCLAS =2 if (mBMI >= 20 & mBMI< 25) replace OBESCLAS =3 if mBMI >= 25.00 label variable OBESCLAS “Classification of Obesity” label define OBESCLAS 1 “Underweight” 2 “Normal” 3 “Overweight” label values OBESCLAS OBESCLAS tabulate OBESCLAS, miss ========================= • Create a frequency table for OBESCLAS. Copy and paste the table into your Word file.
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10. drtamil@gmail.com Statistical Test – Chi Square 3. Conduct the appropriate statistical test to test whether there is any association between – OBESCLAS (Underweight/Normal/Overweight) and – OUTCOME (Y/N). • Copy and paste the appropriate tables along with the interpretation into your Word file.
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14. drtamil@gmail.com Student’s T-test 4. Conduct the appropriate statistical test to test whether there is any association between – BMI (numerical) and – OUTCOME (Y/N). • Copy and paste the appropriate tables along with the interpretation into your Word file.
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18. drtamil@gmail.com Statistical Tests - ANOVA 5. Conduct the appropriate statistical test to find any association between – OBESCLAS (Underweight/Normal/Overweight) and – BIRTHWGT. • Copy and paste the appropriate tables along with the interpretation into your Word file.
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22. drtamil@gmail.com Pearson’s Correlation 6. Assuming that both variables mBMI & BIRTHWGT are normally distributed, • conduct an appropriate statistical test to prove the association between the two variables. • Demonstrate the association using the appropriate chart. Determine the coefficient of determination. • Copy and paste the above charts and your answers into your Word file.
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26. drtamil@gmail.com Simple Linear Regression 7. Conduct Simple Linear Regression using BIRTHWGT as the dependent variable. Try to come out with a formula that will predict the baby’s birthweight based on the mother’s BMI. • y = a + bx • Copy and paste the appropriate tables and supporting chart along with the interpretation into your Word file.
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29. drtamil@gmail.com SLR Results Birthweight = 1.337395 + 0.0604985 mBMI
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32. drtamil@gmail.com Scatter Diagram