Internal and external validity are two ways of testing cause-and-effect relationships. Internal validity is the extent to which you can be confident that a cause-and-effect relationship established in a study cannot be explained by other factors. External validity refers to the extent to which results from a study can be applied (generalized) to other situations, groups, or events.Threats to internal validity are important to recognize and counter in a research design for a robust study. Different threats can apply to single-group and multi-group studies. For example, maturation. The outcomes of the study vary as a natural result of time. For example, most participants are new to the job at the time of the pre-test. A month later, their productivity has improved as a result of time spent working in the position. There are three main factors that might threaten the external validity a study: sampling bias; testing; and Hawthorne effect.
ed directly or indirectly with the war and it is lawful to kill ‘to shelter the innocent from harm…punish evildoers (Begby et al (2006b), Page 290).However, as mentioned above civilian cannot be harmed, showing combatants as the only legitimate targets, another condition of jus in bello, as ‘we may not use the sword against those who have not harmed us (Begby et al (2006b), Page 314).’ In addition, Frowe suggested combatants must be identified as combatants, to avoid the presence of guerrilla warfare which can end up in a higher death count, for example, the Vietnam War. Moreover, he argued they must be part of the army, bear arms and apply to the rules of jus in bello. (Frowe (2011), Page 101-3). This suggests Frowe seeks a fair, just war between two participants avoiding non-combatant deaths, but wouldn’t this lead to higher death rate for combatants, as both sides have relatively equal chance to win since both use similar tactics? Nevertheless, arguably Frowe will argue that combatant can lawfully kill each other, showing this is just, which is also supported by Vittola, who states: ‘it is lawful to draw the sword and use it against malefactors (Begby et al (2006b), Page 309).’
In addition, Vittola expresses the extent of military tactics used, but never reaches a conclusion whether it’s lawful or not to proceed these actions, as he constantly found a middle ground, where it can be lawful to do such things but never always (Begby et al (2006b), Page 326-31). This is supported by Frowe, who measures the legitimate tactics according to proportionality and military necessity. It depends on the magnitude of how much damage done to one another, in order to judge the actions after a war. For example, one cannot simply nuke the terrorist groups throughout the middle-east, because it is not only proportional, it will damage the whole population, an unintended consequence. More importantly, the soldiers must have the right intention in what they are going to achieve, sacrificing the costs to their actions. For example: if soldiers want to execute all prisoners of war, they must do it for the right intention and for a just cause, proportional to the harm done to them. This is supported by Vittola: ‘not always lawful to execute all combatants…we must take account… scale of the injury inflicted by the enemy.’ This is further supported by Frowe approach, which is a lot more moral than Vittola’s view but implies the same agendas: ‘can’t be punished simply for fighting.’ This means one
