is the ability of the instrument to measure what its purpose to measure. Data is valid when it measures or describes what it set up to measure or describe.

-analysis of whether the instrument is using a valid scale -intuitive judgment -measuring what its supposed to primarily based upon the logical link between the questions and the objectives of the study

not to undertake any data collection or analysis methodology that is more complex or expensive than is necessary

is the extent to which similar results are obtained on two separate administrations

The same test given to the group of respondents twice. The scores in the first are correlated to the scores in the second

measures the consistency of results when you repeat the same test on the same sample at different point in time

-study weather they are able to elicit the necessary information -The items and questions cover the full range of the issue or attitude being measured

refers to how well a survey, questionnaire, or test actually measures what you want it to measure. determining how all items on the test relate to all other items.

The extent that its items measure the same trait

-One of the oldest methods for assessing internal consistency -this approach items on a scale are split into two groups and scored independently, scores on the two half are then used to compute a correlation coefficient

is the ability of an instrument to identify a case correctly that is to screen in or diagnosis a condition correctly -true positive

-is the instruments ability to identify non cases correctly that is the screen out those without the condition correctly -true negatives

-refers to the consistency and stability of the results -a reliable instrument deals the same rank for each individual who take the test or more than once

the greater the degree of consistency and stability in an instrument, the greater the blank

it involves establishing that the results of a qualitative research or credible or believable from the perspective of the participant in the research

split-half reliability involves what

as the mood of respondent good change from one interview to another, so could the mood, motivation, and interaction of the interviewer which could affect the responses given by the respondents

in an interview situation, The interaction between the interviewer and the interviewee can affect responses significantly.During the repeat interview responses may be different due to changing interaction which could affect reliability

when a research instrument is used to measure attitudes towards an issue some respondents after having expressed their opinion, may feel that they have been either to negative or two positive towards the issue.

what should be found in the discussion of the formulation of instrument of the study?

this refers to the degree to which the results of qualitative research can be generalized or transferred to other contexts or settings

in the framework suggested by Guba and Lincoln, it is concerned with whether the researcher would obtain the same results if he observes when the same thing twice

refers to the degree to which the results would be confirmed or corroborated by others

it deals with the measures that can be administered and validated at the same time

a slight ambiguity in the wording of questions or statements as respondents may interpret that questions differently at different times resulting in different responses

in the case of an instrument being used in an interview any change in the physical setting at the same time of the repeat interview may affect the responses given by the respondent

a change in respondents mode when responding the questions or writing answers in a questionnaire can change in effect his responses

what are the factors affecting the reliability of a research instrument

is the consistency with which it measures the target attribute

The three key aspects are

the principles in data collection

estimated by having two or more trained observers to watch an event simultaneously and independently recording data according to the instruments instruction

involves the assignment of numbers to represent the amount of an attribute present in an object or person using a specified set of rules

refers to how well the test predicts some future behavior of the examiners

-whether the test corresponds with its theoretical construct -extend to which it is consistent with theoretically derive hypothesis

an expression of how scores from tests are correlated with an external criterion

what are the types of validity