Choose which credible evidence for the sales kit.
Completed projects, testimonials, or result metrics: each type persuades a different audience, and misusing them can diminish credibility instead of enhancing it.
The strongest evidence in a sales kit for businesses is often a case study with quantitative results accompanied by testimonials from individuals in the same industry and role as the reader. Client logos are suitable for initial recognition, but they are not substantial enough to close the deal when the buyer is weighing risks. The core principle is to select evidence that directly addresses the reader's concerns, rather than showcasing everything to everyone.
- You need to convince the person holding the budget at the validation stage.
- Customers worry that the solution does not fit their industry.
- Use a logo wall for quick validation at the awareness level.
- Showcasing a logo unrelated to the reader's industry.
- Generic testimonials without specific results.
Credibility evidence does not mean more is better. The issue is not quantity but alignment: the right type of evidence, presented to the right person, at the right time in the buying process. Providing the wrong type of evidence to the wrong person can lead to doubt instead of trust.
Three types of evidence and their real weight
Not all evidence carries the same weight in the eyes of business buyers. It can be categorized into three tiers to help you navigate.
- Case study with quantitative results: The strongest. Describe the specific project, who the client is, the initial problem, the solution implemented, and measurable results. Results do not necessarily have to be revenue; they can include reduced time, lower costs, increased conversion rates, or any real numbers that are permissible to use.
- Testimonials from industry peers: This is the second strongest type, especially when the buyer is concerned about whether "this solution fits their situation." A genuine statement from a marketing director in the same industry is more convincing than ten self-praising comments.
- Client logo wall: Useful at the initial awareness level, creating a sense of scale. However, if the logos are unrelated to the reader's industry or the reader does not recognize the brand, the effect is almost null.
Choose evidence based on the reader's role
In a business purchasing decision, there are often many participants: direct users, budget decision-makers, and risk managers. Each role has different concerns and requires different types of evidence.
The direct user (team leader, specialist): Prioritizes real experience and similarity. Needs testimonials from someone in the same position, describing the working process and specific feelings.
When you design the sales kit, ask: who will read this page or section? Then select evidence that is appropriate for that person, rather than including everything in one place.
When to use which evidence?
The purchasing process stage also determines the type of evidence needed.
- Step recognition: Wall of logos, number of projects, names of industries served. The goal is to create an impression of scale and rapid coverage.
- Step consideration: Testimonials from the industry, describing the problem and the approach. The goal is to show clients that you understand their situation.
- Validation step, near closing phase: Case studies with quantitative results, independent certifications, process documentation. The goal is to reduce perceived risk, meaning the concern "what if I make the wrong choice."
Social proof operates under uncertainty, where people look to the actions and choices of others to determine what is right for them.
According to Robert Cialdini, Influence: The Psychology of Persuasion
Common mistakes when presenting evidence
- Unrelated logo: The client is a small manufacturing company, and you only use logos from large corporations in different industries. Readers feel alienated and do not see themselves in it.
- General testimonials: "Very satisfied, will recommend more" does not convey anything specific. Testimonials need to include: who is speaking, what they were concerned about, and how the specific results have changed.
- Fabricating or inflating numbers: The risks to reputation and legality are very high. If you don't have real numbers, use honest qualitative descriptions instead of fake figures.
- Using the client's name and words without permission: This is a breach of trust, and using the words or images of a specific individual may also violate the Advertising Law and the Personal Data Protection Law.
Decision checklist
Subject: What credible evidence should be included in the sales kit. Sinh Vũ guide, sinhvu.com
Tick each item that applies or that you can already answer, then print or save as PDF to take with you.
If you have marked most of the signs above, this is the time to discuss in more detail. Sinh Vũ can help you review and propose a direction.
This article provides general information according to the documents in effect as of October 6, 2026. This is not legal advice and does not substitute for a lawyer's opinion for your specific case. Rights and obligations between Sinh Vũ and clients arise only according to the signed contract.
How Sinh Vũ handles your data: see Privacy policy.
References
Intentsify, Social Proof in B2B Marketing; Robert Cialdini, Influence: The Psychology of Persuasion. Practical experience from Sinh Vũ. Advertising Law 2012 (amended 2025); Personal Data Protection Law 91/2025/QH15. This information is for reference only and does not replace legal advice.
Frequently asked questions
If there are no quantifiable case studies, what can be used instead?
You can use honest qualitative testimonials that describe the process and results perceived by past clients, along with their names and specific roles if permitted. Do not fabricate numbers or exaggerate, as the risk to your reputation is very high. Once you have accumulated enough real data, you can add numbers later.
Does the logo of past clients suffice to convince decision-makers?
Usually not enough at the closing stage. A logo wall works well when the reader is not yet familiar with you, meaning at the awareness level. When they are comparing and weighing risks, the decision-maker needs to see results and testimonials from someone they recognize or who is in the same industry.
Do we need to ask permission from previous clients before including their names and quotes in the materials?
You need to ask for permission, preferably in writing. The Advertising Law prohibits the use of images, words, or writings of individuals without their consent, and the Personal Data Protection Law 2025 requires clear consent when using a person's name, title, or image for marketing purposes. The client's logo is their trademark, and previous contracts may contain confidentiality clauses, so it's important to ask beforehand. Using the client's name, logo, or quotes without consent can damage trust and lead to disputes, especially when personal information of a specific individual is involved. It's advisable to develop the habit of asking for permission right after the project ends, when the client is most satisfied. In complex cases, you should consult a lawyer.
This article is for reference. The scope, pricing, and specific commitments of Sinh Vũ are detailed in the proposal and signed contract.