# Q4A · Discuss Brand Development Index and Category Development Index, stating the various combinations of high and low values and their interpretation

Subject: Advertising and Public Relations

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/apr/#tee/papers/paper-2025-05-13/q4a

Canonical: https://deep-learning-study-room.vercel.app/read/apr/tee/papers/paper-2025-05-13--q4a/

Actual TEE paper · 100 marks · Q1 compulsory + any four complete Q2–Q7

### 2025-05-13 · Q4A · Previous-paper question. Discuss Brand Development Index and Category Development Index, stating the various combinations of high and low values and their interpretation. [10 marks]

#### Answer

**Definition.** An index compares a group’s share of users or sales with its share of the population, using 100 as the average benchmark.

**In simple words.** Sales/users ka share population se zyada? Index 100 se upar.

Swipe across the diagram to read its labels ↔

![BDI and CDI: read both, then investigate the market](https://deep-learning-study-room.vercel.app/apr/fig/bdi.3740d6dd92.svg)

Diagram: BDI and CDI: read both, then investigate the market. Labels: BDI and CDI: read both, then investigate the market | BDI and CDI: read both, then investigate the market | High BDI + high CDI | Strong brand concentration in a strong category | area. Consider sustaining the position. | Low BDI + high CDI | Category is strong; investigate why the brand | lags before investing. | High BDI + low CDI | Brand is relatively strong in a weaker category | area. Assess maintenance and profitability. | Low BDI + low CDI | Both are under-represented. Examine causes; do | not assume either guaranteed potential or no | opportunity. | 100 is the average benchmark. These indices are not growth guarantees.

Audience index, BDI and CDI — follow the labels in order.

## Understand it step by step

1. **Audience / user index:** compare the segment’s share of product users with its share of population. The two percentages use their own relevant totals.
2. **BDI:** Brand Development Index compares an area’s share of total brand sales with its share of population.
3. **CDI:** Category Development Index uses total category sales instead of the brand’s sales.
4. **Interpretation:** 100 means proportional representation; above 100 means over-representation; below 100 means under-representation. The notes’ statement that anything below 100 is “average” is imprecise.
5. **Planning:** high CDI with low BDI may reveal a brand opportunity, but first examine competition, distribution and profitability. An index is not a forecast or a proof of causation.



$$
\text{BDI}=\frac{\%\text{ of total brand sales in area}}{\%\text{ of population in area}}\times100
$$





$$
\text{CDI}=\frac{\%\text{ of total category sales in area}}{\%\text{ of population in area}}\times100
$$



## See it in use

#### Illustrative example · One region

An area has 10% of population, 15% of brand sales and 20% of category sales. BDI = 150 and CDI = 200. Brand sales per population share are above average, yet the category is even more concentrated there. That does not by itself reveal the brand’s exact market share.

| BDI | CDI | Interpretation |
| --- | --- | --- |
| High | High | Brand and category over-represented: consider sustaining strength. |
| Low | High | Category strong, brand relatively weak: investigate distribution/positioning/competition. |
| High | Low | Strong brand concentration in a weaker category: assess profitable maintenance. |
| Low | Low | Both under-represented: investigate causes before committing or withdrawing. |

An index of 100 is the average benchmark. These combinations are diagnostic clues, not guaranteed investment rules.

## A small illustration of the formula

The recovered BDI/CDI questions ask for concepts and high/low interpretations; they do not supply numerical data. The following invented values illustrate the formula and are not a separate required PYQ calculation.

Authored illustration: these numbers were chosen to explain a faculty-note concept. No matching supplied-data question was found in the 14 recovered APR papers. Standalone calculation drills are optional practice; their marks are author-set.

## Given

| Population share | Brand-sales share | Category-sales share |
| --- | --- | --- |
| 10% | 15% | 20% |

## To find

Brand and category development indices.

## Formula and why



$$
\text{BDI}=\frac{B_{\%}}{P_{\%}}\times100,\qquad\text{CDI}=\frac{C_{\%}}{P_{\%}}\times100
$$



The common denominator is population share. Only the numerator changes between brand sales and category sales.

## Step-by-step solution

#### Step 1. Substitute for BDI



$$
\text{BDI}=\frac{15}{10}\times100
$$



#### Step 2. Divide and scale BDI



$$
1.5\times100=150
$$



#### Step 3. Substitute for CDI



$$
\text{CDI}=\frac{20}{10}\times100
$$



#### Step 4. Divide and scale CDI



$$
2\times100=200
$$



#### Step 5. Compare each with 100

Both brand and category are over-represented relative to population.

**Final answer:** BDI = 150; CDI = 200.

#### Practical interpretation · What the answer means

Both brand and category are over-represented relative to population. Indices guide further analysis; they do not guarantee future growth or prescribe an automatic budget decision.