Survey to find a mean
Survey to find a proportion
Spearman's Correlation Coefficient
Exercises for Estimating Mean or Proportion
Calculations require StatPgm_2a_Survey.php
Q 1. We wish to establish the range of normal birth weight from our unit. We know, from past records,
that the birth weight is likely to have a mean of 3.6Kg, and Standard Deviation of 0.4Kg.
We need 18, 65, and 249 babies
Q 2. We weighed our babies, and found a mean of 3700g, and Standard Deviation of 450g.
The 95% confidence intervals are 3489g-3911g, 3572g-3828g, 3611g-3789g, and 3638g-3762g
Q 3. We wish to find out how long a patient has to wait before being seen by a doctor in the antenatal clinic.
On questioning, we were told that, roughly, the average is about 20-40 minutes. We interpret this
to be a mean of 30 minutes and Standard Deviation of 5 minutes.
We need to observe 99, 13, and 7 visits
Q 4. We recorded waiting times, and found that the mean time is 35 minutes, with a Standard Deviation of
The 95% confidence intervals of waiting times are 16min-54min, 24min-46min, 28min-42min, and 31min-39min
Q 5. We wish to establish the Caesarean Section rate in hospitals in Hong Kong. As a ball park
figure, we anticipate that the Caesarean Section rate is about 25%
We need 73, 289, 1801, and 7203 deliveries
Q 6. We examine data from a number of hospitals, and found the following data
A 6. Click to show contents
The 95% confidence intervals of CS rates are :
Q 7. We wish to find out the rate of torn perineum in vaginal deliveries, when no instrumental
deliveries or episiotomy is performed. We suspect that this would be 5% in primiparas, and 1% in
We need to observe :
Q 8. We observed 1000 primiparas with 75 torn perineum, and 1000 multiparas deliveries with 12
The 95% confidence intervals of the rate of torn perineum are
Exercises for Correlation and Regression
Calculations for these exercises require StatPgm_2b_CorReg.php
Q 1. Calculate sample size requirements, for both one and two tail model, for
estimating correlation coefficient from 0.1 to 0.9, at 0.1 intervals, using the default p=0.05 and power=0.8
Perform the exercises in Exercises_1.php One Group
Perform the exercises in Exercises_2.php Correlation / regression