# Tests of Significance: How to Remember?

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• Step 1: First look at the type of variable. Is it quantitative or is it qualitative variable?
• Quantitative variable: Can be measured and expressed as ‘mean’ (Ex: Number of children, Height, Weight, mean Hb% etc.)
• Qualitative variable: Cannot be measured but expressed in ‘proportion’ (Ex: Blood group, Severity of anemia, Prevalence of obesity etc.).

• Step 2: See how many groups are discussed in the question. It may be:
• Comparison between 2 groups
• Comparison within 1 group: before & after an intervention.

• Step 3: Give the answer by following the table: ### Tips to remember:

• ‘Quanti’ contains 1 T: So, in ‘Quanti’ variables: T test to be done
• If done between 2 groups: the test of choice is Student’s T test (as the word ‘STUDENT‘ contains 2T)
• If done among >2 groups: test of choice is ANOVA (Remember: QUANTITATIVE – ANOVA)
• If variable is qualitative and done between 2 groups: the test of choice is Chi-Square as ‘Square’ means 2nd power.

Example 1:

The prevalence of DM was 20% in a population. After an awareness campaign of impact of diet on DM, it came down to 13%. Which test of significance should be used?

1. Chi-Square test
2. McNemar test
3. Student’s T test
4. Paired T test.

Explanation:

1. Step 1: Type of variable: Prevalence of DM: Qualitative variable
2. Step 2: Only 1 group: Before & after an intervention
3. Step 3: So, the test of choice is McNemar test.

Example 2:

Mean Hb level in a group of adolescent women was 9.2 gm%. After iron & folic acid tablet supplementation, it goes to 9.6 gm%. Which test of significance should be used?

1. Chi-Square test
2. McNemar test
3. Student’s T test
4. Paired T test.

Explanation:

1. Step 1: Type of variable: Mean Hb levele: Quanti-tative variable (T test)
2. Step 2: Only 1 group: Before & after an intervention
3. Step 3: So, the test of choice is Paired T test.

Example 3:

Mean Hb level in 3 groups of adolescent women was 9.2 gm%. After iron & folic acid tablet supplementation, it goes to 9.6 gm%. Which test of significance should be used?

1. Chi-Square test
2. Student’s T test
3. Paired T test
4. ANOVA test.

Explanation:

1. Step 1: Type of variable: Mean Hb levele: Quantitative variable
2. Step 2: 3 groups involved
3. Step 3: So, the test of choice is ANOVA test (QUANTITATIVE – ANOVA).

1. Dr. Poornima Tiwari says: