FACULTY OF MEDICINE MD1810 (PUBLIC HEALTH-STATISTICS) YEAR 1 (SEMESTER 2)

PROBLEM BASED LEARNING

PBL

Facilitator’s guide

Prepared by

Dr.Mohamed Abdel Rahman

Trigger1

A researcher is interested in determining whether or not review sessions affect exam performance. A review session is administered to a sample of students (9) in an attempt to determine if this has an effect on the exam performance.

Questions1. Any unclear term/words?2. What are the variables in this study? 3. Which is the independent and dependant variable?4. What is the type of the data in this research?

Answers The variables are1-Review sessions = the independent variable 2- Exam performance = the dependant variable.The type of the data is quantitative data since exam performance is a numerical variable

Trigger2

Based on information gathered in previous semesters, we know that the population mean for a given exam is 24.The sample mean is 25, with a standard deviation of 4

Questions1. Any unclear term/words?2. According to the above information what type of tests is suitable in this research? 3. Why you select this test?4. List the categories you will use in your test?

Answers

1- The suitable test is one sample t-test.2- Why this test

A-quantitative datab- the means of the sample and population are knownc- the standard deviation of the population is unknown

3- Sample mean Sample standard deviation.Population mean

Trigger3

We hypothesized about a population mean for students who get a review based on the information from the population who didn’t get a review (μ=24).

Questions1. Any unclear term/words?2. State your hypotheses in this case? 3. What significance level you like to use?4. Is this a one-tailed or two-tailed test? 5. How you will decide whether review session will affect exam performance or not?

Answers 1- H0- null hypothesis =review session will not affect exam performance2- Ha-alternative hypothesis = review session will affect exam performance.3- 5% or 1% or 10%4- Two- tailed test- the effect was not mentioned whether +ve of –ve effect5- If the t-test rejects the null hypothesis there will be an effect whether negative or

positive.

Step 1: State the hypothesesH0: μ=24H1: μ≥24

Step 2: Set the criterion one-tail test or two-tail test=two-tail test

α-=5% df = n-1 = 9-1=8

Step 3: Collect sample data, calculate x and s. From the example we know the sample mean is 25,

with a standard deviation (s) of 4Step 4: Calculate the test statistic

S/√n= 4/√9=4/3=1.33t =26-24/1.33=1.503

Step 5: Reject H0 if t is more extremethan tcrit• The critical value for a one-tailed t-test withdf=8 and α-=5%is 1.86• Will we reject or fail to reject the nullWe fail to reject the null hypothesis Because the calculated t from the sample data is less than critical t value.So our conclusion is review session will not affect exam performance

H0: μ=24