Explain about the Internal consistency reliability

Internal consistency reliability is used to assess the reliability of a summated scale where several items are summated to form a total score. In simple words, every item in scale must measure part of what scale is developed to measure. Various techniques like 'split-half reliability' or 'coefficient alpha' (also called Cronbach's alpha) are used to measure internal consistency reliability. In split-half reliability scale is broken in two halves and resulting half scores are correlated. High correlation between two halves shows higher internal consistency. In case of coefficient alpha the average of all possible split-half coefficients is calculated. Value beyond 0.7 suggests acceptable internal reliability.