# Forum 3

Respond to 2 discussions written by me. They should be labeled 1 and 2 and need to be 150 words in length each. I will provide an example of how they should be written.

1. When a tool of assessment is characterized as reliable it means that it gives the same results each time it is used in the same setting with the same type of subjects; it has consistent or dependable results. Reliability is part of the assessment of validity.
The conditions one might expect an otherwise useful tool of assessment to be unreliable has to do with many things such as variances and measurement error. Variance from true differences is true variance, and variance from irrelevant, random sources is error variance, (Cohen & Swerdlik, 2018). Because error variance may increase or decrease a test score by fluctuating amounts, consistency of the test score and consequently there can be an effect on the reliability. Measurement error can be characterized as being either systematic or random. The term measurement error denotes all of the factors connected with the process of measuring some variable, other than the variable being measured. Random error is a foundation of error in measuring a targeted variable instigated by unpredictable variations and discrepancies of other variables in the measurement process, (Cohen & Swerdlik, 2018). Systematic error denotes a foundation of error in measuring a variable that is typically persistent or proportionate to what is assumed to be the true value of the variable being measured.
The statement, A test is valid means that the test is determined absolute or comparative based on a judgment or approximation of how well a test measures what it signifies to measure in a specific context. It is a judgment based on proof about the suitability of conclusions drawn from test scores. Tests may be shown to be valid within what we would distinguish as reasonable limitations of a considered usage. If the limitations are exceeded, the validity of the test may be questioned.  Absolute validity denotes the agreement between two sets of data measuring the same subject matter with the same units. Relative validity is the degree to which two methods, regardless of units, rank individuals in the same order. A test can be valid at one time and place with one population of test-takers and invalid at another time, in another place, or with another group of test-takers due to bias and fairness. Bias is a factor inherent in a test that systematically prevents accurate, impartial measurement. If there were a test that had only questions on a particular culture, such as Asians, and you gave that test to Latinos, it would be biased towards favoritism of Asians. Fairness is the extent to which a test is used in an impartial, just, and equitable way. Psalm 9:8 tells us, and he judges the world with righteousness; he judges the peoples with uprightness, (ESV). There must be fairness in all tests as that is how God would want us to treat one another.

2. First reliability means dependability or consistency. Reliability refers to consistency in measurement, it is simply consistent. “Reliability refers to the proportion of the total variance attributed to true variance. Reliability is the extent to which measurements are consistent or repeatable” (Cohen & Swerdlik, 2007 pg. 142). When a tool of assessment is characterized by reliable, it means the greater the proportion of the total variance attributed to true variance, the more reliable the test. The assessment has to be assumed to be stable. presumed to yield consistent scores on repeated administration of the same test as well as one equivalent forms of tests (Cohen & Swerdlik, 2007).
If circumstances like “error variance may increase or decrease a test score by varying amounts, consistency of the test score, the reliability can be affected” (Cohen & Swerdlik, 2007 pg. 142). If measurement error occurs then the tool of assessment may prove to be unreliable. “Measurement error refers to collectively all the factors associated with the process of measuring some variable other than the variable being measured” (Cohen & Swerdlik, 2007 pg. 142). Other conditions like random error and systematic error occur during the test are proven unreliable. “Random error is a source of error in measuring a targeted variable caused by unpredictable fluctuations and inconsistencies of other variables in the measurement process. Random errors could conceivably affect test scores range from unanticipated events happening in the test environment . Systematic error refers to a source of error in measuring a variable that is typically consistent and proportionate to what is presumed to be the true value of the variable being measured” (Cohen & Swerdlik, 2007 pg. 142). Measuring instrument itself that has been found to be a source of systemic error. Once it becomes known it becomes predictable and fixable. Other sources of error variance include test construction, administration, scoring and interpretation (Cohen & Swerdlik , 2007).
To prove a test is valid in other words absolute or relative, judgment must be based on evidence about the appropriateness of inferences drawn from test scores. An instruments’ validity is useful for a particular purpose with a particular population. “No test or measurement technique is “universally valid” for all time, for all users, with all types of test taker populations. Rather, tests may be shown to be valid as reasonable boundaries of a contemplated usage” (Cohen & Swerdlik , 2007 pg. 176). The Bible describes as God always been reliable and true. Whatever God says and has done is absolute truth and it has aways been true. It is based on what God has made evident to us. “They know the truth about God because he has made it obvious to them. For ever since the world was created, through everything God has made, they clearly see his invisible qualities his eternal power and divine nature. So they have no excuse for not knowing God (Romans 1:19-20 NLT).

Reference

Cohen, R.J. & Swerdlik, M.E. (2017). Psychological testing and assessment: An introduction to tests and measurement (9th ed.). Boston, MA: McGraw-Hill.

EXAMPLE:
Thanks for posting; I enjoyed reading your ideas about reliability and validity!  As you said, reliability is certainly important when using any tool of assessment.  When a tool of assessment is said to be unreliable, this means that the tool cannot produce consistent results (Cohen & Swerdlik, 2018).  For example, an unreliable watch would fail to display the correct time, which would cause most people to buy a new watch, as this watch could not be used to tell them the time that their work shift starts or the moment their lunch break begins.  Therefore, reliability is an important measure that can determine whether or not a tool of assessment should be used (Cohen & Swerdlik, 2018).
I appreciate how you mentioned that a tests validity can be understood in absolute and relative terms.  Within a particular context and with a particular population, a test can certainly be deemed valid or invalid (Cohen & Swerdlik, 2018).  However, relativity plays a role when a test cannot measure what it claims to measure due to a difference in context and population.  Many tests intentionally and sometimes unintentionally target a particular population, which means that its validity is dependent on the population of test takers (Cohen & Swerdlik, 2018).  As you stated, it is also important to choose the best tool of assessment after evaluating its characteristics and validity.  This requires discernment, but is ultimately necessary in order to make a judgment about how well the tool measures what it claims to measure (Cohen & Swerdlik, 2018). Psalm 119:66 (NIV) gives us a great model of how to ask God for good judgment in this by saying, Teach me knowledge and good judgment, for I trust your commands.