Measuring tools: should always measure several values.

- X-rays and radiological measurements.
- MRI.
- Goniometry (NB: classical goniometers are not validated given their poor reliability).
- Algometry (algometers, VAS, validated questionnaires, etc)
- EMG.
- ECG.
- EEG.
- Blood or urine tests.
- Doppler.
- Use osteopathic diagnostic tests already scientifically validated.

The objective is to estimate the effect of an intervention or technique on pain, mobility, function etc.).

**The study must be experimental controlled randomized, simple or double blind.**

The patient groups, in the intervention or study group and the control group, are patients with the same pathology who are randomly distributed between the two groups. Both groups should be the same and with the same number of people, this is a key factor.

The inclusion/exclusion criteria should be identical for both groups.

Note: by definition the study group and control group cannot be made up of healthy people, it is obligatory to use populations of patients with the same pathology.

The realization of measurements (tests, etc) must be interexaminator with Kappa coefficient (3 or 4 examinators carry out the same steps: the person who carries out the study cannot take part as examinator but can carry out the technique). To employ in this kind of study the purpose of the Kappa coefficient is to show that measurements obtained (outcome) are independent of which obtains them. The operator who carries out the technique must be submitted to a intra-examinator with Kappa

In this case, it is IMPOSSIBLE for the study to be double-blinded since the researcher, if he/she performs the osteopathic technique, knows who has received the real intervention and who has received the false one, the placebo or another different one.

Therefore, as well as blinding the patients, he/she only performs the technique and the result is examined by other observers (several with a known degree of agreement, here the Kappa coefficient would be applied) who in a blinded way (they do not know which technique each patient has received) evaluate the result, that is, the effect.

**Several variables are studied:**

- Principal or dependent variable: Pain, mobility, function, etc.
- Independent variables: age, sex, severity, etc.
- We should remember in this point that these variables can also be:
- Quantitative variables (algometry or VAS): compares means with parametric Student’s t-tests, two groups, or ANOVA if more than two groups.
- Qualitative variables (X ray, Yes/No, present/absent; healed/not healed): compares proportions, Chi-squared.

The normality of the population must study (Smirnov-Kolgorov).

If the distributions are not normal (Gaussian), use non-parametric tests such as the Mann-Whitney U test (2×2) or Kruskall-Wallis test for more than two groups.

This type of statistics should include: mean, mode, median, maximum, minimum, confidence interval ranges, variance, and standard deviation of ALL the variables ALWAYS.

**STUDY AND CONTROL GROUPS: 50 patients**

- Enough patients in each group (and balanced), mimimum 50 patients in each group.
- Depend on the inclusion/exclusion criteria.
- Random samples (systematic chance) if a technique is studied (not of use if the validation of an osteopathic test is studied).

- CONTROL GROUP:50 patients

This is a group of patients with the same inclusion/exclusion factors: the reference group for comparison.

The sample number must be identical to the study group. (If there are minimum differences of n due to randomization, they are admissible if the distribution continues to be normal and there are enough patients).

They may be untreated or given a placebo treatment (according to ethics) or given another treatment (drug protocols, referenced in literature).

- STUDY GROUP:

This is the group we want to study, comparing it to the reference group, in order to find out the validity of a diagnostic test, a technique or a treatment.

All the patients in the group should present exactly the same problem, same lesions, same symptoms, etc.

The intervention (treatment technique, number of sessions, periodical frequency, etc) should be identical for all the members of the group. The type of pathology we are treating should also be standardized (inclusion criteria).