Coursework Psychology Coursework Research Assignment Paper

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1 Find the standard deviation for the following group of scores: 54, 77, 35, 63, and 82.
Mean =4+54+77+35+63+82Sum of deviations =mean- individual values
= 315/6 =48.5-2.5-25.5+17.5-11.5-30.5
=52.5 =-4/6
=-0.67
2 On a measure of depression, the mean is 19, and the standard deviation is 3. What is the z-score for an actual score of 22?
= (22-19)/3
= 1
=0.8413
3 A psychologist has been studying delayed recall of certain words using a new memory measure. On this measure, she has found that the distribution follows a normal curve. What percentage of students have z-scores below 1.2?
Mean=0 and standard deviation=1
z-score= (-x-0)/1 so -1.2<=(x-0)/1
=-1.2<=x
= (-1.2/10)*100
=12%
4 A psychologist has been studying delayed recall of certain words using a new memory measure. On this measure, she has found that the distribution follows a normal curve. The memory test has a mean of 15 words recalled and a standard deviation of 2.5. Using a normal curve table, what score on the memory measure would a person need to have to be in the top 15%?
= 0.15 = ( x - 1 ) / 2.5
= ( 0.15 * 2.5 ) + 1 = x
x = 1.375
5 There is a .9471 correlation between per capita cheese consumption and the number of people who died by becoming tangled in their bedsheets. ( (Links to an external site.)Links to an external site.). How much of the variance in the relationship between these two variables is accounted for?
More than 80% of the variance is accounted for.
Short Answer Essay:
1 Identify and describe two (2) factors that affect reliability coefficients. Be sure to define reliability coefficient in your answer before explaining how the two factors affect reliability coefficients.
* A reliability coefficient is a numerical index for measuring reliability that ranges from 0 to 1, where a number closer to 0 indicates low reliability, and closer to 1 indicates higher reliability.
* The first factor is the variability of subjects. Measurement of reliability may be challenging in the calculation of small-value measurements because of the presence of measurement errors. The errors affect the values obtained in the calculation of reliability coefficients.
* The second factor is obtaining paradoxical results. A measurement may have good reliability according to one coefficient but poor reliability according to another. The discrepancies make the coefficients obtained unreliable.
2 What is the test-retest method of estimating reliability?
The test-retest method is a method of testing for the reliability coefficient for a set of results to determine how consistent the results are over some time by repeating the process of measurement on the same subjects under similar conditions then comparing the observations.
Describe the type of study that would be needed to find evidence of test-retest reliability.
The use of a survey in the form of an interview-reinterview procedure is suitable.
When is this method best used?
The method is suitable when it is possible to repeat the same test over similar subjects and under similar conditions to make comparisons.
When should it not be used?
The method is unsuitable when the information needed is subject to change from the respondent when tested repeatedly among the same subjects.
3 Fully explain the relationship between reliability and validity.
Reliability and validity work together because reliability deals with the consistency of information obtained while validity focuses on the accuracy of information. Measurements can be reliable without being valid but cannot be valid without being reliable
4 Identify the steps of a criterion-related validation study. Be sure to define criterion-related validity in your answer.
Criterion-related validity measures how well a measure predicts a result for another measure. The measure examines the relationship that exists between variables that may be related.
The steps involved are:
* Define a sample size to use for the application of valid and stable correlation coefficients.
* Avail scores from the test and criterion for calculation of correlation coefficients.
* Assess exam reliability.
* Use a measure of performance correlated with test scores because criterion measures tend to be of low quality.
* Restrict ranges for results to possess adequate variability through adequate variatio...