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26 Cards in this Set
- Front
- Back
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What is variance? |
represents the amount of variance in the data |
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There are 3 main methods of representing variability. What are they? |
- Range - standard deviation - Variance |
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What is Correlation? |
Standardized representation of the association between two variables. Can range from -1 to 1 |
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What are composite variables? |
the sum of two or more items |
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The variance of a composite score is a function of __________. |
1:the variance associated with the individual items 2:the correlations amongst the items |
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As the correlation between the items increases (and is positive), the magnitude of the corresponding composite score variance also __________. |
Increases |
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What are binary items? |
- dichotomous items - encountered in achievement type tests - either provide correct or incorrect answers - responses are scored as 0 or 1 |
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True or false: the variance of a dichotomously scored item is maximized when half of the people score 1 and the other half score 0. |
TRUE |
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What are the two most common test score interpretations? |
- relative - abstract |
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To interpret an individual's score, what do we need to do? |
- make reference to an entire distribution of scores on the test - identify where the individual falls within that distribution. i.e Know the mean and SD |
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What is the most commonly used standardised score? |
Z-score |
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what is the mean and SD of z-scores |
M=0 SD=1 |
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to convert raw scores into z-scores, what is the formula? |
z= Score - Mean of score/ SD |
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what are z-scores useful for? |
- Turning raw scores into easily interpretable relative scores. - Compare scores across tests that are on different sized units |
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What is a T-score and why is it better than a z-score? |
-M= 50 SD= 10 - Z-scores can have negative numbers. T-scores dont. |
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What are steps to create T-scores? |
- Convert the raw scores into z-scores - convert the z-scores using the following formula: T =z(10)+50 |
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What do percentile ranks indicate? |
Percentage of scores that are below a specific test score |
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What are the 3 ways to represent scores in relative terms |
- z-scores - T-scores - percentile ranks |
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What are probability samples? |
it ensures that there are representative samples |
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What are closed ended questions? |
questions which asks respondents to choose from a fixed set of response alternatives. (quantitative) eg Multiple choice questions, yes/no and questions with numerical rating scale |
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What are open ended questions? |
Dont provide repondents with any reponse alternatives (Qualitative). |
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What are the advantages of likert scales? |
- efficient to create - analysed statistically - respondents have experience with scales - lot of info can be collected in a short amount of time |
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What are the pros and cons of closed ended questions? |
Pros: - fast and easy - restrict range of responses Cons: - restricted to reponses that may not account to how they feel. - force people to express an opinion when they might not have one |
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What are the pros and cons of open ended questions? |
Pros: - Convey info that inst captured in fixed answer format - Express precise feelings/attitudes - indepth answers - gives sense that their opinion matters Cons: - slow - not quantitative |
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What are negatively keyed items? |
negatively keyed item entails that the person is denying or negating the attribute of interest. |
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What are double barrelled items? |
asks two or more questions in the same item which may be expected to be answered differently |
