1. Describe the difference between stratified sampling and systemic sampling. Use example whenever necessary.

Stratified sampling Systemic sampling
• Sub-groups are present in the universe • Number the items in the universe
• The candidates for the sample are chosen according to some regular patterns. • It may happen that a population under study falls naturally into sub-groups or strata

• Example: Estimating the survival rate of trauma victim in a large hospital. Suppose the hospital has Level 1, Level 2 and Level 3 trauma centre. We wish to take samples from these trauma centres with sample size of 30. • Example:
Select every 10th member from a list of population

2. Compare and discuss the descriptive statistics for bar graph and histogram.

Bar graph Histogram graph
• Type of graph is indicated for qualitative and quantitative discrete data. • Method of choice for quantitative continuous data.
• The distance between bars is kept equal to or less than the breadth of the bars. • The centres of top of each rectangle are joined by a line.
• The frequency shown on Y-axis (vertical bar) or on the X-axis (horizontal bars). • The frequency shown X-axis (class interval) and Y-axis (frequency per unit of class interval) Graphical presentation method to display da ta or information in a well organized style.

3. List and compare the three different types of tables in the context of biostatistics

Textual tables

• Often use when dealing with qualitative