study in Finland examined maternal liquorice consumption during pregnancy and its effects on pubertal outcomes in children.

QUESTION 1

 A study in Finland (Räikkönen et al. 2017) examined maternal licorice consumption during pregnancy and its effects on pubertal outcomes in children.

 Licorice consumption is thought to be higher in Finland than in other European countries due to the popularity of salmiakki, a salty liquorice snack. Liquorice contains a chemical called glycyrrhizin which has been shown in animal models to alter the timing of puberty.

 Participants were recruited from an urban community-based cohort of women and their healthy, singleton infants born in 1998 in Helsinki, Finland. The average age of the children at the time of the study was 12.5 years. Low maternal consumption of glycyrrhizin during pregnancy was defined as ≤249 mg/week. High maternal consumption of glycyrrhizin during pregnancy was defined as ≥500 mg/week. 

One of the measures taken to estimate age of puberty was a child’s height. Analyses of pubertal development were conducted separately in girls and boys because adolescent girls are, on average, ahead of boys in pubertal development. 451 of the participants in the study were girls. Their height measurements are shown in

Table 1.1 below.

Table 1.1:      Girls’ mean height by level of maternal consumption of glycyrrhizin in liquorice during pregnancy, Helsinki, Finland, 2009– 2011

(a)  Do girls born to mothers with low consumption of glycyrrhizin during pregnancy or girls born to mothers with high consumption of glycyrrhizin during pregnancy have the larger variation in height? Explain your answer.       

(Question 1 continues on the next page)(b)

i. What is the difference in mean height between the low consumption and high consumption groups?

ii. Calculate the standard error of this difference.     

iii. Use these answers to calculate the 95% confidence interval for this difference.                                                      

iv.  What evidence does this confidence interval provide, that in the population from which the sample was taken, girls whose mothers consumed high amounts of glycyrrhizin in pregnancy have on average a greater height at aged 12.5 years than girls whose mothers consumed low amounts of glycyrrhizin in pregnancy?                                                 

(c)           Carry out a statistical test for the difference in height between girls whose mothers consumed low amounts of glycyrrhizin in pregnancy and girls whose mothers consumed high amounts of glycyrrhizin in pregnancy. Remember to state your null hypothesis, show your working and interpret your results. (30%)

 When considering their results, the researchers also looked at data from another cohort of women and similarly aged children in Finland. This cohort was recruited from a rural area. In the rural cohort the mean difference in heights between girls whose mothers consumed zero-low amounts of glycyrrhizin in pregnancy and girls whose mothers consumed high amounts of glycyrrhizin in pregnancy was 4.9cm 95% CI (1.92, 11.64cm).

(d)

i.   Is this difference in mean height significantly different (at p<0.05) from the difference in mean height in the urban cohort?             

ii. Was the sample size of the rural cohort larger or smaller than that in the urban cohort? You can assume that the standard deviations were similar. 

Note: it is not necessary to carry out more calculations for question (d), but you should give reasons for your answers.

(Question 2 starts on the next page)

Word limit: up to 1000 words per the whole question (equivalent to approximately 2 pages of typed text with size 11 font)