Validity and Reliability

Validity and Reliability
I am writing a report, there are some questions I do not understand. Please explain

1. How did the researchers assess the RELIABILITY of this survey, & what did they find?

2. How did the researchers assess the VALIDITY of this survey, what did they find, how can the validity of physical activity questionnaires be addressed.

Correct me if I am wrong. The rationale and main purpose of this article
The rationale of this survey was that most surveys are not sensitive to address lower range of physical activity for older people. Surveys should be adopted for use in countries with different languages and cultures

Purpose of article “ to make questions understandable and have participants consider all activities equally relevant, and meet requirements for a valid age specific questionnaire for older people to measure regular physical activity , and establish internal validity and testing against adequate criteria for low intensity behaviors .

To summarize this article: the Spanish version of this survey was given to a gp of healthy noninstitutionalized elderly. Lg gp of elderly subjects, from middle socio economic class, middle years of education.. Need for survey was to measure current physical activity (quality and quantity) among the older population. Problem w/questionnaire is environment in which it is performed. They are influenced by cultural factors.