A study was conducted to identify factors that can cause small for gestational age (SGA) babies. One of the factors studied was the mother's body mass index (BMI). It is believed that mothers with a lower BMI are at higher risk of having SGA babies. The document provides instructions to analyze a dataset using STATA to examine the relationship between mother's BMI and birthweight. This includes calculating mean and standard deviation of BMI, classifying BMI levels, conducting statistical tests to analyze associations between variables, and building a linear regression model to predict birthweight based on mother's BMI.

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http://pubhealthcollo.org/drtamil
/stata/p76990.dta
https://drtamil.me/2015/06/04/
fk6193-computer-based-
examination-cbe-stata/

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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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Mean & Standard Deviation

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Summarise

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Results

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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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Copy Paste Into Command

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Resultsof“Tabulate”

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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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Pearson Chi-Square

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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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Student’s T-test

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Student’sT-test

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Student’s T-test Results

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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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Statistical Tests - ANOVA

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ANOVA

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ANOVA Results

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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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Pearson’s Correlation

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Correlation Results

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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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Simple Linear Rgression

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SLR Results
Birthweight = 1.337395 + 0.0604985 mBMI

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Scatter Diagram

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Scatter Diagram