Introduction
Part 1 : Q1.1 to 1.15
Part 1 : Q1.16 to 1.23
Part 2 : Q2.1 to 2.6
Part 2:Q2.16 to 2.30
The assessment exercise for the BSc. Midwifery consists of a series of questions that the students must correctly answer. The reasoning, guidelines, and marking guides are presented in the Guidelines to Assessment page.
This page contains the questions to be answered, and these are common to all Midwifery students. Each student however will received a unique set of data, in the form of an excel file, to be used to answer these questions.
The assessment is in two parts.
 Part 1 covers all basic statistical procedures taught in the module. When all exercises in Part 1 are successfully completed, the student will have pass the module with a grade of C or D
 Part 2 contains more complex exercises, sometimes requiring more than one statistical procedure and sometimes requiring some handling of the data. When all exercises are completed in Part 1 and Part 2, the student will be considered for the grade of A or B.
Students should place their answers in a Word or pdf file, write protect the contents with a password, then submit it attached to an email to Prof. Chang. Students are reminded that
 There is no limit to the number of submissions, but the number of submissions required before passing will
affect grading. Specifically
 Student will be graded D if more than 3 submissions are required before passing Part 1
 Student will have priority in being considered for grade B if both Part 1 and 2 are passed with earlier submissions
 Student will only be considered for grade A if both Part 1 and 2 are passed with the first submission
 Students may submit their answers as soon after July 2015 as they choose, but are reminded that
 Student must successfully pass Part 1 by the end of March, 2018, will be graded F for failure.
 30% of those graded C are awarded B or better, and 30% of these are awarded A. Once qualified for
consideration, the higher grades are awarded in order of the time of the final submission until the quota is filled.
Finally, be aware that all data used in assessment, in fact, all data used in the statistics module, are computer generated and not real
Q1.1
Q1.2
Q1.3
Q1.4
Q1.5
Q1.6
Q1.7
Q1.8
Q1.9
Q1.10
Q1.11
Q1.12
Q1.13
Q1.14
Q1.15
Question 1.1 : Produce a Pie Chart
The student is required to produce a pie chart using the data in worksheet A in his/her unique Excel file
The table contains the numbers of different type of deliveries in a hospital over 1 year
The minimum acceptable standards of the pie chart produced are as follows
 Each wedge of the pie must have a different color or shading
 The color or shading must be labelled with
 The group the wedge is associated with. The wording need not be exact, but should be clearly interpretable
 The percent of total. The percentage should be accurate to 1 decimal point, e.g. 12.3%
 One wedge of the pie (it does not matter which one) should be separated from the whole pie
Question 1.2 : Produce a Fixed Interval Bar Chart
The student is required to produce a bar chart using the data in worksheet A in his/her unique Excel file
The table contains the numbers of different type of deliveries in a hospital over 1 year
The minimum acceptable standards of the bar chart produced are as follows
 The widths of the bars are the same in the chart, and the intervals between the bars are the same in the chart
 The width of the bars are approximately the same as the interval between them
 The x axis
 What the x axis represents should be named
 The name for each bar is clearly labelled. The names need not be the same as that in the data but must be clearly interpretable
 If a name is too long, it should be split up into two rows
 The center of the name should align with the center of the bar
 The y axis
 What the y axis represents should be named
 The y axis should be the number of cases and not percentages
 The major intervals should be regular, in multiples of 2, 5, 10, or 100
 The minor intervals should be immediately interpretable
Question 1.3 : Sample Size and Precision of Proportions
The student is required to produce a table of sample size and precision estimations, using the data in worksheet A in his/her unique Excel file
The table should be constructed as follows
 The rows
 The top row should contains the labels for each column
 The subsequent rows are for each type of delivery or each cause of abdominal pain, according to which table of data is used
 The columns, counting from the left
 Column 1 is the label for type of delivery
 Column 2 is the number of cases, copied from the data
 Column 3 is the percentage of the total
 Column 4 is the 95% confidence interval of the percentage, in term of percent
 Column 5 is the sample size required in a survey to confirm the percentage, with a 95% confidence interval of ±1%
 Column 6 is the sample size required in a survey to confirm the percentage, with a 95% confidence interval of ±5%
The minimum acceptable standards of the table
 All labels must be clearly interpretable
 All percentages have precision up to 1 decimal point. e.g. 12.3%
 All columns and rows are clearly separated and aligned.
Question 1.4 : Normally Distributed Measurements
The student is required to analyse a set of normally distributed measurements and tabulate the results, using the height of mothers in worksheet B.
The student should analyse the data and produce a table showing the following results
 Sample size
 Mean
 Standard Deviation
 95% confidence interval of the measurement
 Standard Error of the mean
 Precision of the mean, the ± error of mean at the 95% confidence level
 95% confidence interval of the mean
The minimum acceptable standards of the table
 The tables should be two columns, the label and the value
 Labels must be clearly interpretable
 Values should have precision of 1 decimal point. e.g. 3500.3
 All columns and rows are clearly separated and aligned.
Question 1.5 : Calculation of percentile values
Based on the results of analysis in Question 1.4, the student is required to produce a table showing the value for the 5 ^{th}, 10 ^{th}, 90 ^{th}, and 95 ^{th} percentile
The minimum acceptable standards of the table
 The table should be two columns, the label and the value
 Labels must be clearly interpretable
 Values should have precision of 1 decimal point. e.g. 3500.3
 All columns and rows are clearly separated and aligned.
Question 1.6 : Calculation Sample size for estimating means
Based on the results of analysis in Question 1.4, the student is required to produce a table showing the sample size required in a survey to confirm the mean value with an error at half of current error, at the current error, and at double the current error
The minimum acceptable standards of the table
 The table should be two columns, the label and the sample size
 Labels must be clearly interpretable
 All columns and rows are clearly separated and aligned.
Question 1.7 : Calculation z scores and percentile of values
Based on the data used and results of analysis in Question 1.4, the student is required to produce a table showing the t score (number of Standard Deviation from the mean) and percentile for each value
 The table should have 3 columns
 Column 1 shows the value from the data
 Column 2 shows the t score, t = (valuemean) / Standard Deviation
 Column 3 shows the percentile value
The minimum acceptable standards of the table
 The data is shown as obtained
 t scores should have a 2 decimal point precision
 Percentile should be to the nearest whole number
 All columns and rows are clearly separated and aligned.
Question 1.8. Correlation Analysis
The student is required to perform correlation analysis, using gestation and birth weight data in worksheet C.
The data is in two columns. The first column are gestational age in weeks, and the second column birth weight in grams.
The student should analyse the data and produce a table showing the following results
 Assuming birth weight is normally distributed, the Pearson's correlation Coefficient ρ
 The 95% confidence interval of ρ, calculated using Fisher's Z Transformation, both one and two tails
The minimum acceptable standards of the table
 The tables should be two columns, the label and the value
 Labels must be clearly interpretable
 Values should have precision of 4 decimal point. e.g. 0.3456
 For 95% confidence interval, the two tail model, the range of the interval is required
 For 95% confidence interval, the one tail model, the ranges for the left tail and the right tail are required
Question 1.9. Sample size for estimation Correlation Coefficient
Based on the correlation coefficient ρ obtained in Question 1.8, create a table showing the sample size required (one and two tail model), to estimate correlation coefficients with the value obtained in Question 1.8, half its value, and a third its value.
The minimum acceptable standards of the table
 The tables should be 3 columns, ρ, sample size (1 tail), and sample size (two tail)
 In addition to the row with labels, the table should have 3 rows, for ρ obtained in Question 1.8, ρ/2, and ρ/3
Question 1.10. Regression Analysis
The student is required to perform regression analysis, using gestation and birth weight data in worksheet C.
The data is in two columns. The first column are gestational age in weeks, and the second column birth weight in grams.
The student should carry out a regression analysis and obtain the formula y = a + bx, where x is gestation in weeks, and y birth weight in grams.
Both the constant a and regression coefficient b should have precision to 4 decimal points.
Based on the regression formula obtained, the student should calculate the mean birth weight at weekly interval from 36 weeks to 42 weeks (inclusive).
Birth weights should be calculated to the nearest whole number of grams.
Question 1.11. Scatter Plot and Regression Line
The student is required to produce a scatter plot, using gestation and birth weight data in worksheet C.
The data is in two columns. The first column are gestational age in weeks, and the second column birth weight in grams.
The minimum standard of the plot are as follows
 The x axis should represent gestation (weeks), with major interval 2 weeks and minor interval 1 week
 The y axis birth weight (grams), with major interval 1000g and minor interval 200g
 Both x and y intervals are clearly marked and labelled.
 A regression line, extending from 36 weeks to 42 weeks should be drawn.
Question 1.12 : Nonparametric Correlation : Spearman's Correlation Coefficient
The data in Worksheet D is a two column table of Likert Scores, each row is data from a woman in the postnatal ward, and each column is her response to a statement.
 Column 1 is the response to the statement "My recent labour was painful"
 Column 2 is the response to the statement "I received good care during my recent labour"
The responses are
 1:SD = Strongly Disagree
 2:D = Disagree
 3:N = Neutral
 4:A = Agree
 5:SA = Strongly Agree
Assuming that Likert Scores are ordered but not normally distributed, the student is required to construct a table correlating the two
Likert scales. The student is also require to calculate the nonparametric Spearman's Correlation Coefficient, its statistical significance, and interpretat the results.
The standards required for the table are as follows
 The rows represents the responses to Likert 1
 The columns represents the responses to Likert 2
 Each cell represents the number of cases that responded to that Likert 1 and 2
 The rows and columns are clearly labelled
The standards required for the results of analysis are
 The Spearman's Correlation Coefficient should have a precision of 4 decimal places
 The Probability of Type I Error should have a precision of 2 decimal places, or "not significant" if p>0.05
 Student should conclude whether a significant correlation exists between the two Likert Scores, and if so, whether the correlation is positive or negative.
Question 1.13 : Comparing two parametric measurements
The table in worksheet E is a two column table. Each row representing data from a new born. Column 1 represents the sex of the baby, (boy or girls), and column 2 the birth weight (grams).
The data is used to test the hypothesis that boys weigh more than girls at birth.
The student is required to analyse the data and produce the following results
 The sample size (n), mean, and Standard Deviation of birth weight for boys and for girls
 The difference in mean birth weight between the two sexes
 The 95% confidence interval of the difference, the two tail, the left of the one tail, and the right of the one tail
 Whether there is a significant difference between the two sexes (two tail conclusion)
 Whether boys are significantly heavier than girls (one tail,right)
 Whether girls are significantly heacier than boys (one, tail left)
Birth weight should be presented to the nearest gram
Question 1.14 : Sample size comparing two parametric measurements
Based on the difference between the two means obtained in question 1.13, the student is required to calculate the sample size (per group) for comparing that difference, if the within group Standard Deviations is 350g, 400g, or 450g. The sample size required for both the one and two tail models should be calculated
Question 1.15 : Data Plot comparing two groups
The table in worksheet E is a two column table. Each row representing data from a new born. Column 1 represents the sex of the baby, (boy or girls), and column 2 the birth weight (grams).
The student is required to produce a data plot showing the relationship between the two groups.
The standards of the plot are as follows
 The x axis represents the two groups
 The y axis represents birth weight
 Both x and y axis should be clearly marked and labelled.
 All data points should be seen. Where thee are 2 or more cases in a group with the same value,the data points should be shifted
slightly, so that no data point is completely obscured.
 The mean, 95% confidence interval of measurements, and 95% confidence interval of the means in the two groups should be marked.
Q1.16
Q1.17
Q1.18
Q1.19
Q1.20
Q1.21
Q1.22
Q1.23
Q1.24
Q1.25
Q1.26
Q1.27
Q1.28
Q1.29
Q1.30
Question 1.16 : Nonparametric comparison of two measurements
The data in worksheet F is a two column table.
 The rows represents data from each woman in labour
 Column 1 represents whether the woman is a primipara (having her first baby) or a multipara (have had a previous baby)
 Column 2 represents duration of labour in 6 groups.
The student is required to analyse the data and produce the following
 A table of frequencies of duration of labour in the two groups. The standard of the table are as follows
 The top row contains labels for parity
 The left most column contains labels for duration of labour in groups
 The cells contains the number of women for that combination of parity and duration of labour, and the percentage of the
total of that parity group (column total)
 The labels must be clear and immediately interpretable
 The percentage should have a precision to 1 decimal point
 The U value in the Robust Rank Ordered Test (used to be called Mann Whitney U Test), comparing the two parity groups, and the probability of the Type I Error
 An interpretation
 Whether there is a significant difference in duration of labour between the two parity groups, and if so,
which group has longer labours.
 An explanation for the conclusions
Question 1.17 : Risk Difference
The data in worksheet G is from a controlled trial comparing the use of prostaglandins and oxytocin to induce labour near term.
 Cases are randomly allocated to two groups, group 1 to receive prostaglandins and group 2 to receive oxytocin.
 The results are designated as + for success and  for failure. Success is reaching established labour within 12 hrs of induction
without the need for further medication or obstetric procedures
 The research hypothesis to be tested is that prostaglandins results in a higher proportion of successful inductions.
The data is a 2 column table
 The rows represents data from each woman in the trial
 Column 1 represents the treatment group, prostaglandins or oxytocin
 Column 2 represents outcome, either success or failure.
The student is required to analyse the data comparing the two proportions (risk difference), and produce the following results
 The risk (proportion) of success in the two groups
 The difference in risks (proportions) between the two groups
 The 95% confidence interval of the difference, the two tails interval, the left tail and right tail of the one tail model
 The numbers needed to treat to change the outcome of a single case
 Interpret the statistical results in terms of the research hypothesis
The standard of the answers are as follows
 Proportions (risks) are to be presented as percentage, with one decimal point precision
 Numbers needed to treat are to be presented rounded upwards to the next whole number. e.g. 2.1 rounded upwards to 3
Question 1.18 : Odds Ratio
The data from worksheet H are a number of retrospective studies to test the research hypothesis that vaccination is a cause of autism.
Children with (+) and without () autism were recruited, and their history of vaccination (+ or ) examined.
The table in worksheet H contains results from a number of studies, where the number of children with and without autism and vaccination are listed.
 column 1 (Autistic+,Vaccinated+) are the number of children with autism and were vaccinated
 Column 2 (Autistic+,Vaccinated) are the number of children with autism but were not vaccinated
 Column 3 (Autistic,Vaccinated+) are the number of children with no autism and were vaccinated
 Column 4 (Autistic,Vaccinated) are the number of children with no autism and were not vaccinated
The student is required to perform analysis using Odds Ratio for each of the studies, and produce a table showing the following
 The odd of vaccination in the autistic group and nonautistic group
 The Log(Odds Ratio) and its Standard Error
 The 95% confidence interval of the Odds Ratio
 Interpret the results in term of the research hypothesis, whether children with autism were more likely to have been vaccinated
The standard of the table are as follows
 The rows and columns are clearly labelled.
 Each row represents results from a study
 Odds and ratios should have a precision of 4 decimal places
 Interpretation should be whether the results "supported" or "not supported" the research hypothesis
Question 1.19 : Metaanalysis
Using the results obtained in question 1.18, perform a metaanalysis to answer the following questions
 Whether the studies are heterogeneous or not
 Whether publication bias should be suspected or not
 Combine the data to produce the summary effect size and its 95% confidence interval, using the Random Effect Model
 Provide an interpretation of the collective results as to whether the conclusions should be accepted or whether significant
flaws exists in the data used.
Question 1.20 : Forest Plot
Using the results obtained in question 1.19, produce a Forest Plot to represent the data and the combined Effect size.
The plot should have the following standards
 The x axis should be the Odds ratio and not log(odds ratio)
 The x axis should be adequately marked and scaled
 Each study should be represented by a mark for the odds ratio, and a line marking the 95% confidence interval
 The marks for the data and the summary effect should be different
 There should be a vertical line to mark the null value of 1
Question 1.21 : Prediction and Diagnosis
A study is carried out to assess the quality of prediction using the unengaged head at the beginning of labour to predict delivery by
Caesarean Section.
The table in worksheet I contains the results of such a study
 Column 1 are those delivered by Caesarean Section, and column 2 those by vaginal delivery
 Row 1 are those with unengaged head at the beginning of labour, and row 2 those with engaged head at the beginning of labour
The student is required to analyse the quality of prediction, using the unengaged head to predict Caesarean Section. The standard required are as follows
 The True and false Positive and Negative Rates, in percentages, to a precision of 1 decimal places
 The Likelihood Ratios for Test Positive and Negative, to a precision of 4 decimal places
Question 1.22 : Posttest Probability
Using the results ontained in question 1.21, predict the probability of Caesarean Section in the following situations
 When the head is unengaged at the beginning of labour
 In a hospital where the overall Caesarean Section rate is 25%
 In a hospital where the overall Caesarean Section rate is 45%
 When the head is engaged at the beginning of labour
 In a hospital where the overall Caesarean Section rate is 25%
 In a hospital where the overall Caesarean Section rate is 45%
Percentage should be to a precision of 1 decimal place
Question 1.23 : Receiver Operator Characteristics (ROC)
A study is carried out using maternal height to predict Caesarean Section> The results of the study are in the table in worksheet J
 Column 1 is the maternal height in cms, to a precision of 1 decimal place
 Column 2 is the mode of delivery, being wither Caesarean Section (CS) or vaginal delivery (VD)
The student is required to analyse the data and produce the following'
 The area under the Receiver Operator Characteristics curve (θ) and its 95% confidence interval
 A 3 row table showing the common cut off values
 The rows are where
 The test has maximum accuracy, where the Youden Index is maximum
 The test can be used as a screening tool, where the ratio True Positive Rate/True Negative Rate is closest to 3
 The test can be used as a action decision tool, where the ratio True Negative Rate/True Positive Rate is closest to 3
 The columns are for values to be listed, including
 Maternal Height, in cm to 1 decimal place precision
 The False and True Positive Rates, in percent to 1 decimal place precision
 The Likelihood Ratios for test positive and test negative, to 4 decimal place precision
 Discuss how these cut off values are to be used clinically, if the student is in charge of the labour ward
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Q2.1
Q2.2
Q2.3
Q2.4
Q2.5
Q2.6
Q2.7
Q2.8
Q2.9
Q2.10
Q2.11
Q2.12
Q2.13
Q2.14
Q2.15
Question 2.1 : Plot Data Distribution
Based on the data used and results of analysis in Question 1.7, the student is required to summarize then produce a distribution plot of the t scores. The student may carry this out in any way he/she chooses providing the final plot is produced. However, the following sequence is suggested to assist the students that have initial difficulties
 Each t score is converted to the nearest whole number 2, 1, 0, 1, and 2
 The whole number scores are summarized into a table of counts for each value
 The number of cases in each whole number is converted to a percentage of total
 A bar plot is produced with the x axis being the whole number t value, and the y axis the percentage
Only the plot needs to be shown. However the student may also show the intermediary calculations so that errors (if any) can be traced.
The minimum acceptable standards of the plot
 The plot is a Bar Chart
 The x axis represents t values in groups of nearest whole number with each bar labelled
 The y axis is the percent of total for each bar, marked with major intervals of 10% and minor intervals of 2% or 5%
 The bars have the same width and are clearly separated from each other
Question 2.2 : Paired Difference in Parametric Measurements
The data in worksheet L contains the birth weight of twins, column 1 (Twin_1) is the twin that is delivered first, and column 2 (Twin_2) is the twin that delivered second.
The data is obtained to test the hypothesis that the order of birth in twins are related to their relative weights, so that a difference in birth weight exists between the first born and second born twin.
The student is required to analyse the data to test this hypothesis, assuming that birth weight is normally distributed. The standard of the answers are as follows
 The results required are the sample size, mean, Standard Deviation, Standard Error of the Mean, and the 95% confidence interval of the mean for the paired difference.
 The conclusions to be drawn from this statistics.
 Birth weight parameters should be presented to a precision of the nearest gram.
Question 2.3 : Plotting Receiver Operator Characteriscs (ROC)
Using result obtained from Question 1.23, the student is required to produce a plot for the Receiver Operator Characteristics. The standard required are
 The x axis is the False Negative Rate
 The y axis is the True Positive Rate
 Both axis must be clearly marked and labelled. The rates can either be in percent or as a number from 0 to 1
 The ROC curve is drawn
 A diagonal line joining where the two rates are 0 and are 1
 Data points (circular or square) where
 The test has maximum accuracy, where the Youden Index is maximum
 The test can be used as a screening tool, where the ratio True Positive Rate/True Negative Rate is closest to 3
 The test can be used as a action decision tool, where the ratio True Negative Rate/True Positive Rate is closest to 3
Question 2.4 : Complex Posttest Probabilities
Using the results of analysis from questions 1.21 and 1.23, the student is required to calculate the probability of Caesarean Section under the following circumstances
 In a hospital with an overall Caesarean Section rate of 25%
 where maternal height is less than that where Youden Index is maximum
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 where maternal height is more than that where Youden Index is maximum
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 where maternal height is less than where the ratio True Positive Rate/True Negative Rate is closest to 3
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 where maternal height is more than where the ratio True Positive Rate/True Negative Rate is closest to 3
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 where maternal height is less than where the ratio True Negative Rate/True Positive Rate is closest to 3
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 In a hospital with an overall Caesarean Section rate of 45%
 where maternal height is less than that where Youden Index is maximum
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 where maternal height is more than that where Youden Index is maximum
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 where maternal height is less than where the ratio True Positive Rate/True Negative Rate is closest to 3
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 where maternal height is more than where the ratio True Positive Rate/True Negative Rate is closest to 3
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
 where maternal height is less than where the ratio True Negative Rate/True Positive Rate is closest to 3
 When the head is not engaged at the beginning of labour
 When the head is engaged at the beginning of labour
The results should be in a clearly labelled table where
 Column 1 is the overall Caesarean Section Rate
 Column 2 is the maternal height
 Column 3 is whether the head is unengaged or engaged
 Column 4 is the probability of Caesarean Section
 Probabilities should be in percent, with 1 decimal point precision
Question 2.5 : Covariance Analysis
Worksheet K contains a table of 3 columns
 Column 1 the sex of the newborn
 Column 2 gestational age in weeks
 Column 3 birthweight in grams
The student is required to perform a covariance analysis on the data and produce the following results
 The mean and Standard Deviation of the birth weight for boys and girls
 The difference in birth weight between the sexes, and its 95% confidence interval
 The difference in birth weight between the sexes, and its 95% confidence interval, after adjusting for the effects of
gestation on the birthweights
 Comment on the methodology used, and whether there is any flaws or pitfalls in the methodologies
The birth weight and gestations should be presented with the precision to the nearest whole number
Question 2.6 : Complex x/y data plot
The student is required to plot the data from worksheet K, to demonstrate the complex relationship between sex, gestation, and birthweight.
The plot should conform to the following standards
 The data from boys and girls should be separated by colors and positions so they can be clearly seen
 Three regression lines should be drawn, one for each sex, and one for the two sexes combined
 The x and y axis should be clearly marked and labelled in units of multiples of 2, 5, or 10
 The colors for sexes and regression lines should be clearly labelled
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Q2.16
Q2.17
Q2.18
Q2.19
Q2.20
Q2.21
Q2.22
Q2.23
Q2.24
Q2.25
Q2.26
Q2.27
Q2.28
Q2.29
Q2.30
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