MGTO 231Human Resources

Management

Personnel selection I

Dr. Kin Fai Ellick WONG

Questions for you

• The objective of selection is very simple:– Choosing the “correct” person

• However, we do not have magic, there are often many “incorrect choices” in our decisions

• A more realistic objective for selection seems to be:– Minimizing the probability of making an incorrect selection– How?

• I hope you will get some insights at the end of this class

Outline

• In Personnel selection I– The basic concepts– Measurement errors– Reliability

• In Personnel selection II– Validity – Selection tools

• Letter of recommendation, ability tests, personality tests, interviews, handwriting analysis, etc.

Outline

Selection I

Basic Concepts Measurement errors Reliability

Selection as prediction

• I want to have employees with good performance

• I cannot know their performance before hiring

• I can just predict from applicants’ various characteristics

• Some individuals are more likely to have better performance than others (remember the idea of individual differences)

What are the predictors

• Any characteristics associated with individual differences– Age, gender, IQ, EQ, interpersonal skills,

education level, openness, extroversion, academic performance, etc.

– Some may be better predictors than others (more reliable and valid)

• All selection methods are to measure these characteristics and the associations between these characteristics with different aspects of performance

• Selection individual characteristics performance

• Tools predictors performance

• Two major issues in selection– How consistent is the prediction

(reliability)– How well is the prediction (validity)

• Is it really measuring what it is supposed to measure?

An example of a good and a bad predictor

Y

Academic Results

Job Performance

Y

Interview’s rating

Job Performance

Which one has positive relationship with job performance?

Outline

Selection I

Basic Concepts Measurement errors Reliability

Measurement errors

• Please answer questions 1 and 2

Measurement errors

• Error is not equal to mistake

• Error is a kind of inaccuracy and variability

• Error can be reduced if the measuring device is precise, but it cannot be completely eliminated

• Observed score = – True score + systematic errors + random errors

• Systematic errors– A constant is added to every measure– Observed score = True score + constant

• Random errors– A random value is added to every measure– The random values are normally distributed,

with mean = 0– Observed score = True score + random value

Sources of errors

• Systematic errors– Basic characteristics of the measuring device

• Random errors– Physical

• Temperature, humanity, loudness, brightness, etc.

– Psychological• Fatigue, motivation, adaptation to new environments

– Sampling error• domain sampling model

Outline

Selection I

Basic Concepts Measurement errors Reliability

Reliability (可靠度 )

• Definition– (Textbook) The consistency of scores

obtained by the same person when retested with the identical or equivalent tests

Measurement errors and reliability

• Which kind of errors, systematic or random, may affect the reliability of a measurement?

• The purpose of testing– Assessing individual difference– The influence of systematic errors on this purpose

is, everyone’s score is biased by a constant. The relative performance is unchanged

• Low T always gets low X, and high T always gets high X

– The influence of random errors:• Low T may obtain high X, and high T may obtain low X• The probability of Low T getting high X increases as

random error increases

What is a reliable measurement?

• A test that can truly reflect the “True score” is claimed as a reliable test

• For a perfectly reliable test– The correlation between the true score (T) and

the observed score (X) is 1– X can be fully accounted by T

• For a perfectly unreliable test– The correlation between T and X is 0– T accounts for nothing about X

• Tests that are relatively free of measurement (random) errors are deemed to be reliable

• There is much less concern with systematic errors

• The term “errors” usually refers to random errors

Which one is more reliable?

– Tests that are relatively free of measurement random errors are deemed to be reliable

– Reliability refers to consistency of measurement or repeatability

Trial Thermometer A Thermometer B Thermometer C

1 101 103 108

2 99 97 108

3 100 102 107

4 101 103 108

5 99 95 108

Methods measuring reliability

• Test-retest

• Parallel/alternate forms

• Split half

• Alpha (internal consistency)

• How do you interpret this picture?– Please tell me a story about the picture

• Is this test reliable? – Why?

Conclusion

• I’ve asked:– A more realistic objective for selection seems to

be:• Minimizing the probability of making an incorrect

selection• How?

• Step 1:Using test with high reliability– Checking the reliability before and after using

• I’ll discuss the other step about “validity” in next lesson