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| === Dependent and Independent Variables === | | === Dependent and Independent Variables === |
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| An independent variable, sometimes called an | | An independent variable, sometimes called an |
| experimental or predictor variable, is a variable that is being | | experimental or predictor variable, is a variable that is being |
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| dependent variable, sometimes called an outcome variable. | | dependent variable, sometimes called an outcome variable. |
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| Imagine that a tutor asks 100 students to complete | | Imagine that a tutor asks 100 students to complete |
| a maths test. The tutor wants to know why some students perform | | a maths test. The tutor wants to know why some students perform |
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| dependent and independent variables for the study are: | | dependent and independent variables for the study are: |
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| Dependent Variable: Test Mark (measured from 0 to | | Dependent Variable: Test Mark (measured from 0 to |
| 100) | | 100) |
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| Independent Variables: Revision time (measured in | | Independent Variables: Revision time (measured in |
| hours) Intelligence (measured using IQ score) | | hours) Intelligence (measured using IQ score) |
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| The dependent variable is simply that, a variable | | The dependent variable is simply that, a variable |
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| (this simply doesn't make sense). | | (this simply doesn't make sense). |
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| Therefore, the aim of the tutor's investigation is | | Therefore, the aim of the tutor's investigation is |
| to examine whether these independent variables - revision time and IQ | | to examine whether these independent variables - revision time and IQ |
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| in some way. | | in some way. |
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| In the section on experimental and | | In the section on experimental and |
| non-experimental research that follows, we find out a little more | | non-experimental research that follows, we find out a little more |
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| === Experimental and Non-Experimental Research === | | === Experimental and Non-Experimental Research === |
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| Experimental research: In experimental research, | | Experimental research: In experimental research, |
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| asked to do 20 hours of revision in the two weeks prior to the test. | | asked to do 20 hours of revision in the two weeks prior to the test. |
| The tutor could then compare the marks that the students achieved. | | The tutor could then compare the marks that the students achieved. |
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| Non-experimental research: In non-experimental | | Non-experimental research: In non-experimental |
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| understand the different characteristics amongst variables. This is | | understand the different characteristics amongst variables. This is |
| discussed next. | | discussed next. |
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| === Categorical and Continuous Variables === | | === Categorical and Continuous Variables === |
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| Categorical variables are also known as discrete | | Categorical variables are also known as discrete |
| or qualitative variables. Categorical variables can be further | | or qualitative variables. Categorical variables can be further |
| categorized as either''' nominal, ordinal or dichotomous.''' | | categorized as either''' nominal, ordinal or dichotomous.''' |
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| '''Nominal variables''' are variables that have | | '''Nominal variables''' are variables that have |
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| by district. In this case there will be many more levels of the | | by district. In this case there will be many more levels of the |
| nominal variable (30 in fact). | | nominal variable (30 in fact). |
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| '''Dichotomous variables''' are nominal | | '''Dichotomous variables''' are nominal |
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| "type of property" would be a dichotomous variable. | | "type of property" would be a dichotomous variable. |
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| '''Ordinal variables''' are variables that have | | '''Ordinal variables''' are variables that have |
| two or more categories just like nominal variables only the | | two or more categories just like nominal variables only the |
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| that "They are OK" is twice as positive as "Not very | | that "They are OK" is twice as positive as "Not very |
| much" for example. | | much" for example. |
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| Continuous variables are also known as | | Continuous variables are also known as |
| quantitative variables. Continuous variables can be further | | quantitative variables. Continuous variables can be further |
| categorized as either interval or ratio variables. | | categorized as either interval or ratio variables. |
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| '''Interval variables''' are variables for which | | '''Interval variables''' are variables for which |
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| 20C and 30C is the same as 30C to 40C. However, temperature measured | | 20C and 30C is the same as 30C to 40C. However, temperature measured |
| in degrees Celsius or Fahrenheit is NOT a ratio variable. | | in degrees Celsius or Fahrenheit is NOT a ratio variable. |
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| '''Ratio variables''' are interval variables but | | '''Ratio variables''' are interval variables but |
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| of measurements. So, for example, a distance of ten metres is twice | | of measurements. So, for example, a distance of ten metres is twice |
| the distance of 5 metres. | | the distance of 5 metres. |
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| === Ambiguities in classifying a type of variable === | | === Ambiguities in classifying a type of variable === |
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| In some cases, the measurement scale for data is | | In some cases, the measurement scale for data is |
| ordinal but the variable is treated as continuous. For example, a | | ordinal but the variable is treated as continuous. For example, a |
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| this is a cause of great dispute. | | this is a cause of great dispute. |
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| It is worth noting that how we categorise | | It is worth noting that how we categorise |
| variables is somewhat of a choice. Whilst we categorised gender as a | | variables is somewhat of a choice. Whilst we categorised gender as a |
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| continuous variable. | | continuous variable. |
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| == Enrichment Activities == | | == Enrichment Activities == |
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